fix: swap toRemove & toAdd in deltaExtensions

When we try to remove & add the same extension in a very short
timeframe, it does not get initialized properly because it gets both
added to `toRemove` and `toAdd`. When that happens, the extension is
first added, and then immediately removed. By swapping `toRemove` and
`toAdd` we ensure that the extension is first removed, and then newly
added.

src/service-override/extensions.ts

@@ -433,14 +433,14 @@ export class SimpleExtensionService extends AbstractExtensionService implements
 
   public async deltaExtensions (toAdd: IExtensionWithExtHostKind[], toRemove: IExtension[]): Promise<void> {
     const extHostPicker = (this._extensionHostKindPicker as LocalBrowserExtensionHostKindPicker)
+    for (const extension of toRemove) {
+      extHostPicker.removeForcedExtensionHostKind(extension.identifier.id)
+    }
     for (const extension of toAdd) {
       if (extension.extHostKind != null) {
         extHostPicker.setForcedExtensionHostKind(extension.identifier.id, extension.extHostKind)
       }
     }
-    for (const extension of toRemove) {
-      extHostPicker.removeForcedExtensionHostKind(extension.identifier.id)
-    }
 
     await this._handleDeltaExtensions(new DeltaExtensionsQueueItem(toAdd, toRemove))
   }