fix: set cache tags on 404 pages

Author: mrstork

src/run/handlers/cache.cts

@@ -123,10 +123,6 @@ export class NetlifyCacheHandler implements CacheHandlerForMultipleVersions {
   private captureCacheTags(cacheValue: NetlifyIncrementalCacheValue | null, key: string) {
     const requestContext = getRequestContext()
 
-    if (!cacheValue) {
-      return
-    }
-
     // Bail if we can't get request context
     if (!requestContext) {
       return
@@ -142,6 +138,13 @@ export class NetlifyCacheHandler implements CacheHandlerForMultipleVersions {
       return
     }
 
+    // Set cache tags for 404 pages as well so that the content can later be purged
+    if (!cacheValue) {
+      const cacheTags = [`_N_T_${key === '/index' ? '/' : encodeURI(key)}`]
+      requestContext.responseCacheTags = cacheTags
+      return
+    }
+
     if (
       cacheValue.kind === 'PAGE' ||
       cacheValue.kind === 'PAGES' ||