fix add after dispose issues

src/vs/editor/contrib/snippet/snippetController2.ts

@@ -208,7 +208,7 @@ export class SnippetController2 implements IEditorContribution {
 		this._inSnippet.reset();
 		this._hasPrevTabstop.reset();
 		this._hasNextTabstop.reset();
-		dispose(this._snippetListener);
+		this._snippetListener.clear();
 		dispose(this._session);
 		this._session = undefined;
 		this._modelVersionId = -1;

src/vs/editor/contrib/suggest/suggestController.ts

@@ -149,6 +149,7 @@ export class SuggestController implements IEditorContribution {
 	}
 
 	dispose(): void {
+		this._alternatives.dispose();
 		this._toDispose.dispose();
 		this._widget.dispose();
 		this._model.dispose();