Fix GetObjectHandler to match HeadObjectHandler pattern

Add safety check for nil objectEntryForSSE before tag-based policy
evaluation, ensuring tag-based conditions are always evaluated rather
than silently skipped if entry is unexpectedly nil.

Addresses review comment from Copilot.

weed/s3api/s3api_object_handlers.go

@@ -634,25 +634,30 @@ func (s3a *S3ApiServer) GetObjectHandler(w http.ResponseWriter, r *http.Request)
 	}
 	entryFetchTime = time.Since(tEntryFetch)
 
+	// Safety check: entry must be valid before tag-based policy evaluation
+	if objectEntryForSSE == nil {
+		glog.Errorf("GetObjectHandler: objectEntryForSSE is nil for %s/%s (should not happen)", bucket, object)
+		s3err.WriteErrorResponse(w, r, s3err.ErrInternalError)
+		return
+	}
+
 	// Re-check bucket policy with object entry for tag-based conditions (e.g., s3:ExistingObjectTag)
-	if objectEntryForSSE != nil {
-		identityRaw := s3_constants.GetIdentityFromContext(r)
-		var identity *Identity
-		if identityRaw != nil {
-			var ok bool
-			identity, ok = identityRaw.(*Identity)
-			if !ok {
-				glog.Errorf("GetObjectHandler: unexpected identity type in context for %s/%s", bucket, object)
-				s3err.WriteErrorResponse(w, r, s3err.ErrInternalError)
-				return
-			}
-		}
-		principal := buildPrincipalARN(identity)
-		if errCode, _ := s3a.checkPolicyWithEntry(r, bucket, object, string(s3_constants.ACTION_READ), principal, objectEntryForSSE.Extended); errCode != s3err.ErrNone {
-			s3err.WriteErrorResponse(w, r, errCode)
+	identityRaw := s3_constants.GetIdentityFromContext(r)
+	var identity *Identity
+	if identityRaw != nil {
+		var ok bool
+		identity, ok = identityRaw.(*Identity)
+		if !ok {
+			glog.Errorf("GetObjectHandler: unexpected identity type in context for %s/%s", bucket, object)
+			s3err.WriteErrorResponse(w, r, s3err.ErrInternalError)
 			return
 		}
 	}
+	principal := buildPrincipalARN(identity)
+	if errCode, _ := s3a.checkPolicyWithEntry(r, bucket, object, string(s3_constants.ACTION_READ), principal, objectEntryForSSE.Extended); errCode != s3err.ErrNone {
+		s3err.WriteErrorResponse(w, r, errCode)
+		return
+	}
 
 	// Check if PartNumber query parameter is present (for multipart GET requests)
 	partNumberStr := r.URL.Query().Get("partNumber")