this should help with #402

src/js/assets.js

@@ -142,10 +142,21 @@ var cachedAssetsManager = (function() {
                 details.error = 'Error: ' + lastError.message;
                 console.error('µBlock> cachedAssetsManager.load():', details.error);
                 cbError(details);
-            } else {
+                return;
+            }
+            // Not sure how this can happen, but I've seen it happen. It could
+            // be because the save occurred while I was stepping in the code
+            // though, which means it would not occur during normal operation.
+            // Still, just to be safe.
+            if ( bin[cachedContentPath] === undefined ) {
+                details.error = 'Error: not found';
+                delete entries[path];
+                vAPI.storage.set({ 'cached_asset_entries': entries });
+                cbError(details);
+                return;
+            }
             details.content = bin[cachedContentPath];
             cbSuccess(details);
-            }
         };
         var onEntries = function(entries) {
             if ( entries[path] === undefined ) {

src/js/storage.js

@@ -636,22 +636,32 @@
         µb.updater.restart(nextUpdate);
     };
 
-    // https://github.com/gorhill/uBlock/issues/226
-    // Whitelist in memory.
-    // Whitelist parser needs PSL to be ready.
-    var onWhitelistReady = function() {
-        onAllDone();
-    };
+    var filtersReady = false;
+    var whitelistReady = false;
 
     // Filters are in memory.
     // Filter engines need PSL to be ready.
     var onFiltersReady = function() {
-        µb.loadWhitelist(onWhitelistReady);
+        filtersReady = true;
+        if ( whitelistReady ) {
+            onAllDone();
+        }
+    };
+
+    // https://github.com/gorhill/uBlock/issues/226
+    // Whitelist in memory.
+    // Whitelist parser needs PSL to be ready.
+    var onWhitelistReady = function() {
+        whitelistReady = true;
+        if ( filtersReady ) {
+            onAllDone();
+        }
     };
 
     // Load order because dependencies:
     // User settings -> PSL -> [filter lists, user whitelist]
     var onPSLReady = function() {
+        µb.loadWhitelist(onWhitelistReady);
         µb.loadFilterLists(onFiltersReady);
     };