diff --git a/src/lib/integrationTests/suites/performanceTests.ts b/src/lib/integrationTests/suites/performanceTests.ts
index 948faea6..284d6ed8 100644
--- a/src/lib/integrationTests/suites/performanceTests.ts
+++ b/src/lib/integrationTests/suites/performanceTests.ts
@@ -56,7 +56,7 @@ export const performanceTestSuite: TestSuite = {
 
           // Set performance thresholds (in milliseconds)
           const threshold = 1000; // 1 second
-          const warnings = [];
+          const warnings: string[] = [];
 
           if (parksDuration > threshold) {
             warnings.push(`Parks query slow: ${parksDuration}ms`);
@@ -229,7 +229,7 @@ export const performanceTestSuite: TestSuite = {
 
           // Performance threshold: 200ms for simple functions
           const threshold = 200;
-          const warnings = [];
+          const warnings: string[] = [];
 
           if (modDuration > threshold) {
             warnings.push(`is_moderator slow: ${modDuration}ms`);
diff --git a/src/lib/integrationTests/suites/submissionTests.ts b/src/lib/integrationTests/suites/submissionTests.ts
index 33eaec16..34c26998 100644
--- a/src/lib/integrationTests/suites/submissionTests.ts
+++ b/src/lib/integrationTests/suites/submissionTests.ts
@@ -347,7 +347,7 @@ export const submissionTestSuite: TestSuite = {
           }
 
           // Verify version was created with images
-          let version = null;
+          let version: any = null;
           const pollStart = Date.now();
           while (!version && Date.now() - pollStart < 5000) {
             const { data } = await supabase
diff --git a/src/lib/integrationTests/suites/unitConversionTests.ts b/src/lib/integrationTests/suites/unitConversionTests.ts
index e52d9e83..25e4949a 100644
--- a/src/lib/integrationTests/suites/unitConversionTests.ts
+++ b/src/lib/integrationTests/suites/unitConversionTests.ts
@@ -72,16 +72,16 @@ export const unitConversionTestSuite: TestSuite = {
           // Validate values are stored in metric
           const tolerance = 0.01; // Allow small floating point differences
           
-          if (Math.abs(ride.max_speed_kmh - testData.max_speed_kmh) > tolerance) {
+          if (Math.abs((ride.max_speed_kmh ?? 0) - testData.max_speed_kmh) > tolerance) {
             throw new Error(`max_speed_kmh mismatch: expected ${testData.max_speed_kmh}, got ${ride.max_speed_kmh}`);
           }
-          if (Math.abs(ride.max_height_meters - testData.max_height_meters) > tolerance) {
+          if (Math.abs((ride.max_height_meters ?? 0) - testData.max_height_meters) > tolerance) {
             throw new Error(`max_height_meters mismatch: expected ${testData.max_height_meters}, got ${ride.max_height_meters}`);
           }
-          if (Math.abs(ride.length_meters - testData.length_meters) > tolerance) {
+          if (Math.abs((ride.length_meters ?? 0) - testData.length_meters) > tolerance) {
             throw new Error(`length_meters mismatch: expected ${testData.length_meters}, got ${ride.length_meters}`);
           }
-          if (Math.abs(ride.height_requirement - testData.height_requirement) > tolerance) {
+          if (Math.abs((ride.height_requirement ?? 0) - testData.height_requirement) > tolerance) {
             throw new Error(`height_requirement mismatch: expected ${testData.height_requirement} cm, got ${ride.height_requirement}`);
           }
 
@@ -172,7 +172,7 @@ export const unitConversionTestSuite: TestSuite = {
           tracker.track('rides', rideId);
 
           // Poll for version creation
-          let version = null;
+          let version: any = null;
           const pollStart = Date.now();
           while (!version && Date.now() - pollStart < 5000) {
             const { data } = await supabase
@@ -193,13 +193,13 @@ export const unitConversionTestSuite: TestSuite = {
 
           // Validate version has metric units
           const tolerance = 0.01;
-          if (Math.abs(version.max_speed_kmh - 120.0) > tolerance) {
+          if (Math.abs((version.max_speed_kmh ?? 0) - 120.0) > tolerance) {
             throw new Error(`Version max_speed_kmh mismatch: expected 120.0, got ${version.max_speed_kmh}`);
           }
-          if (Math.abs(version.height_meters - 60.0) > tolerance) {
+          if (Math.abs((version.height_meters ?? 0) - 60.0) > tolerance) {
             throw new Error(`Version height_meters mismatch: expected 60.0, got ${version.height_meters}`);
           }
-          if (Math.abs(version.height_requirement_cm - 140) > tolerance) {
+          if (Math.abs((version.height_requirement_cm ?? 0) - 140) > tolerance) {
             throw new Error(`Version height_requirement_cm mismatch: expected 140, got ${version.height_requirement_cm}`);
           }
 
diff --git a/src/lib/integrationTests/suites/versioningTests.ts b/src/lib/integrationTests/suites/versioningTests.ts
index 13a0e727..a8a6e748 100644
--- a/src/lib/integrationTests/suites/versioningTests.ts
+++ b/src/lib/integrationTests/suites/versioningTests.ts
@@ -43,7 +43,7 @@ export const versioningTestSuite: TestSuite = {
           parkId = park.id;
           
           // Poll for version creation
-          let v1 = null;
+          let v1: any = null;
           const pollStart = Date.now();
           while (!v1 && Date.now() - pollStart < 5000) {
             const { data } = await supabase
@@ -243,7 +243,7 @@ export const versioningTestSuite: TestSuite = {
           parkId = park.id;
           
           // Poll for version creation
-          let v1 = null;
+          let v1: any = null;
           const pollStart = Date.now();
           while (!v1 && Date.now() - pollStart < 5000) {
             const { data } = await supabase
diff --git a/src/lib/notificationService.ts b/src/lib/notificationService.ts
index ef27107e..76701097 100644
--- a/src/lib/notificationService.ts
+++ b/src/lib/notificationService.ts
@@ -347,8 +347,8 @@ class NotificationService {
       return (data || []).map(t => ({
         ...t,
         is_active: t.is_active ?? true,
-        description: t.description || undefined,
-        novu_workflow_id: t.novu_workflow_id || undefined
+        description: t.description || null,
+        novu_workflow_id: t.novu_workflow_id || null,
       }));
     } catch (error: unknown) {
       logger.error('Error fetching notification templates', {
diff --git a/src/lib/requestTracking.ts b/src/lib/requestTracking.ts
index 7f277933..100967a3 100644
--- a/src/lib/requestTracking.ts
+++ b/src/lib/requestTracking.ts
@@ -110,7 +110,7 @@ async function logRequestMetadata(metadata: RequestMetadata): Promise<void> {
   // Safe cast - RPC function exists in database
   const { error } = await supabase.rpc('log_request_metadata' as 'log_request_metadata', {
     p_request_id: metadata.requestId,
-    p_user_id: metadata.userId || null,
+    p_user_id: metadata.userId ?? undefined,
     p_endpoint: metadata.endpoint,
     p_method: metadata.method,
     p_status_code: metadata.statusCode,
diff --git a/src/lib/submissionItemsService.ts b/src/lib/submissionItemsService.ts
index b15bb2ab..ba097097 100644
--- a/src/lib/submissionItemsService.ts
+++ b/src/lib/submissionItemsService.ts
@@ -1450,7 +1450,7 @@ export async function checkSubmissionConflict(
       },
       serverVersion: {
         last_modified_at: data.last_modified_at,
-        last_modified_by: data.last_modified_by,
+        last_modified_by: (data.last_modified_by ?? undefined) as string,
         modified_by_profile: data.profiles as any,
       },
     };
diff --git a/src/pages/AdminDashboard.tsx b/src/pages/AdminDashboard.tsx
index 72d7ed8c..3c54c53b 100644
--- a/src/pages/AdminDashboard.tsx
+++ b/src/pages/AdminDashboard.tsx
@@ -197,7 +197,7 @@ export default function AdminDashboard() {
       onRefresh={handleRefresh}
       refreshMode={refreshMode}
       pollInterval={pollInterval}
-      lastUpdated={lastUpdated}
+      lastUpdated={lastUpdated ?? undefined}
       isRefreshing={isRefreshing}
     >
       <div className="space-y-6">
diff --git a/src/pages/AdminModeration.tsx b/src/pages/AdminModeration.tsx
index fb1906c5..5dea1bbf 100644
--- a/src/pages/AdminModeration.tsx
+++ b/src/pages/AdminModeration.tsx
@@ -37,7 +37,7 @@ export default function AdminModeration() {
         onRefresh={handleRefresh}
         refreshMode={refreshMode}
         pollInterval={pollInterval}
-        lastUpdated={lastUpdated}
+        lastUpdated={lastUpdated ?? undefined}
       >
         <div className="space-y-6">
           <div>
@@ -70,7 +70,7 @@ export default function AdminModeration() {
       onRefresh={handleRefresh}
       refreshMode={refreshMode}
       pollInterval={pollInterval}
-      lastUpdated={lastUpdated}
+      lastUpdated={lastUpdated ?? undefined}
     >
       <div className="space-y-6">
         <div>
diff --git a/src/pages/AdminReports.tsx b/src/pages/AdminReports.tsx
index 785c3cc9..4aa2dbaa 100644
--- a/src/pages/AdminReports.tsx
+++ b/src/pages/AdminReports.tsx
@@ -38,7 +38,7 @@ export default function AdminReports() {
         onRefresh={handleRefresh}
         refreshMode={refreshMode}
         pollInterval={pollInterval}
-        lastUpdated={lastUpdated}
+        lastUpdated={lastUpdated ?? undefined}
       >
         <div className="space-y-6">
           <div>
@@ -71,7 +71,7 @@ export default function AdminReports() {
       onRefresh={handleRefresh}
       refreshMode={refreshMode}
       pollInterval={pollInterval}
-      lastUpdated={lastUpdated}
+      lastUpdated={lastUpdated ?? undefined}
     >
       <div className="space-y-6">
         <div>
diff --git a/src/pages/Auth.tsx b/src/pages/Auth.tsx
index ce460ae8..212993d5 100644
--- a/src/pages/Auth.tsx
+++ b/src/pages/Auth.tsx
@@ -147,7 +147,7 @@ export default function Auth() {
       const { handlePostAuthFlow } = await import('@/lib/authService');
       const postAuthResult = await handlePostAuthFlow(data.session, 'password');
 
-      if (postAuthResult.success && postAuthResult.data.shouldRedirect) {
+      if (postAuthResult.success && postAuthResult.data?.shouldRedirect) {
         // Get the TOTP factor ID
         const { data: factors } = await supabase.auth.mfa.listFactors();
         const totpFactor = factors?.totp?.find(f => f.status === 'verified');
@@ -189,7 +189,7 @@ export default function Auth() {
         errorMessage = 'Invalid email or password. Please try again.';
       } else if (errorMsg.includes('Email not confirmed')) {
         errorMessage = 'Please confirm your email address before signing in.';
-      } else if (error.message.includes('Too many requests')) {
+      } else if (error instanceof Error && error.message.includes('Too many requests')) {
         errorMessage = 'Too many login attempts. Please wait a few minutes and try again.';
       }
       
diff --git a/src/pages/BlogIndex.tsx b/src/pages/BlogIndex.tsx
index 59731e6e..d502013b 100644
--- a/src/pages/BlogIndex.tsx
+++ b/src/pages/BlogIndex.tsx
@@ -45,8 +45,8 @@ export default function BlogIndex() {
     description: searchQuery 
       ? `Search results for "${searchQuery}" in ThrillWiki Blog` 
       : 'News, updates, and stories from the world of theme parks and roller coasters',
-    imageUrl: data?.posts?.[0]?.featured_image_url,
-    imageId: data?.posts?.[0]?.featured_image_id,
+    imageUrl: data?.posts?.[0]?.featured_image_url ?? undefined,
+    imageId: data?.posts?.[0]?.featured_image_id ?? undefined,
     type: 'website',
     enabled: !isLoading
   });
@@ -97,14 +97,14 @@ export default function BlogIndex() {
                   slug={post.slug}
                   title={post.title}
                   content={post.content}
-                  featuredImageId={post.featured_image_id}
+                  featuredImageId={post.featured_image_id ?? undefined}
                   author={{
                     username: post.profiles.username,
-                    displayName: post.profiles.display_name,
-                    avatarUrl: post.profiles.avatar_url,
+                    displayName: post.profiles.display_name ?? undefined,
+                    avatarUrl: post.profiles.avatar_url ?? undefined,
                   }}
                   publishedAt={post.published_at!}
-                  viewCount={post.view_count}
+                  viewCount={post.view_count ?? 0}
                 />
               ))}
             </div>
diff --git a/src/pages/BlogPost.tsx b/src/pages/BlogPost.tsx
index bcf05d1c..251968f6 100644
--- a/src/pages/BlogPost.tsx
+++ b/src/pages/BlogPost.tsx
@@ -23,7 +23,7 @@ export default function BlogPost() {
       const query = supabase
         .from('blog_posts')
         .select('*, profiles!inner(username, display_name, avatar_url, avatar_image_id)')
-        .eq('slug', slug)
+        .eq('slug', slug || '')
         .eq('status', 'published')
         .single();
 
@@ -41,8 +41,8 @@ export default function BlogPost() {
   useOpenGraph({
     title: post?.title || '',
     description: post?.content?.substring(0, 160),
-    imageUrl: post?.featured_image_url,
-    imageId: post?.featured_image_id,
+    imageUrl: post?.featured_image_url ?? undefined,
+    imageId: post?.featured_image_id ?? undefined,
     type: 'article',
     enabled: !!post
   });
@@ -106,14 +106,14 @@ export default function BlogPost() {
         <div className="flex items-center justify-between mb-8 pb-6 border-b">
           <div className="flex items-center gap-3">
             <Avatar className="w-12 h-12">
-              <AvatarImage src={post.profiles.avatar_url} />
+              <AvatarImage src={post.profiles.avatar_url ?? undefined} />
               <AvatarFallback>
                 {post.profiles.display_name?.[0] || post.profiles.username[0]}
               </AvatarFallback>
             </Avatar>
             <div>
               <p className="font-medium">
-                {post.profiles.display_name || post.profiles.username}
+                {post.profiles.display_name ?? post.profiles.username}
               </p>
               <div className="flex items-center gap-3 text-sm text-muted-foreground">
                 <div className="flex items-center gap-1">
diff --git a/src/pages/DesignerDetail.tsx b/src/pages/DesignerDetail.tsx
index e8218551..af7e5be0 100644
--- a/src/pages/DesignerDetail.tsx
+++ b/src/pages/DesignerDetail.tsx
@@ -46,9 +46,9 @@ export default function DesignerDetail() {
   // Update Open Graph meta tags
   useOpenGraph({
     title: designer?.name || '',
-    description: designer?.description || (designer ? `${designer.name} - Ride Designer${designer.headquarters_location ? ` based in ${designer.headquarters_location}` : ''}` : ''),
-    imageUrl: designer?.banner_image_url,
-    imageId: designer?.banner_image_id,
+    description: designer?.description ?? (designer ? `${designer.name} - Ride Designer${designer.headquarters_location ? ` based in ${designer.headquarters_location}` : ''}` : ''),
+    imageUrl: designer?.banner_image_url ?? undefined,
+    imageId: designer?.banner_image_id ?? undefined,
     type: 'profile',
     enabled: !!designer
   });
@@ -71,7 +71,7 @@ export default function DesignerDetail() {
       const { data, error } = await supabase
         .from('companies')
         .select('*')
-        .eq('slug', slug)
+        .eq('slug', slug || '')
         .eq('company_type', 'designer')
         .maybeSingle();
 
@@ -197,10 +197,10 @@ export default function DesignerDetail() {
               <picture>
                 <source 
                   media="(max-width: 768px)" 
-                  srcSet={getBannerUrls(designer.banner_image_id).mobile || designer.banner_image_url} 
+                  srcSet={(getBannerUrls(designer.banner_image_id ?? undefined).mobile || designer.banner_image_url) ?? undefined} 
                 />
                 <img 
-                  src={getBannerUrls(designer.banner_image_id).desktop || designer.banner_image_url} 
+                  src={(getBannerUrls(designer.banner_image_id ?? undefined).desktop || designer.banner_image_url) ?? undefined} 
                   alt={designer.name}
                   className="w-full h-full object-cover"
                   loading="eager"
@@ -244,12 +244,12 @@ export default function DesignerDetail() {
                   </div>
                 </div>
                 
-                {designer.average_rating > 0 && (
+                {(designer.average_rating ?? 0) > 0 && (
                   <div className="bg-black/30 backdrop-blur-md rounded-lg p-6 text-center">
                     <div className="flex items-center gap-2 text-white mb-2">
                       <Star className="w-6 h-6 fill-yellow-400 text-yellow-400" />
                       <span className="text-3xl font-bold">
-                        {designer.average_rating.toFixed(1)}
+                        {(designer.average_rating ?? 0).toFixed(1)}
                       </span>
                     </div>
                     <div className="text-white/90 text-sm">
@@ -361,14 +361,14 @@ export default function DesignerDetail() {
                 id: designer.id,
                 name: designer.name,
                 slug: designer.slug,
-                description: designer.description,
+                description: designer.description ?? undefined,
               company_type: 'designer',
               person_type: (designer.person_type || 'company') as 'company' | 'individual' | 'firm' | 'organization',
-              website_url: designer.website_url,
-                founded_year: designer.founded_year,
-                headquarters_location: designer.headquarters_location,
-                banner_image_url: designer.banner_image_url,
-                card_image_url: designer.card_image_url
+              website_url: designer.website_url ?? undefined,
+                founded_year: designer.founded_year ?? undefined,
+                headquarters_location: designer.headquarters_location ?? undefined,
+                banner_image_url: designer.banner_image_url ?? undefined,
+                card_image_url: designer.card_image_url ?? undefined
               }}
               onSubmit={handleEditSubmit}
               onCancel={() => setIsEditModalOpen(false)}