Ensure that md5 and assetId stay in sync.

src/serialization/serialize-assets.js

@@ -19,7 +19,7 @@ const serializeAssets = function (runtime, assetType) {
             const storage = runtime.storage;
             const storedAsset = storage.get(assetId);
             assetDescs.push({
-                fileName: assetType === 'sound' ?
+                fileName: currAsset.md5 ?
                     currAsset.md5 : `${assetId}.${storedAsset.dataFormat}`,
                 fileContent: storedAsset.data});
         }

src/virtual-machine.js

@@ -537,6 +537,7 @@ class VirtualMachine extends EventEmitter {
         // If we're in here, we've edited an svg in the vector editor,
         // so the dataFormat should be 'svg'
         costume.dataFormat = storage.DataFormat.SVG;
+        costume.md5 = `${costume.assetId}.${costume.dataFormat}`;
         this.emitTargetsUpdate();
     }