cleanup dispose

src/browser/services/DecorationService.ts

@@ -126,9 +126,13 @@ export class Decoration extends Disposable implements IDecoration {
         if (this.isDisposed) {
           return;
         }
-        this._container.removeChild(this._element!);
+        if (!this.marker.isDisposed) {
+          this.marker.dispose();
+        }
+        if (this._element) {
+          this._container.removeChild(this._element);
+        }
         this.isDisposed = true;
-        this._marker.dispose();
         // Emit before super.dispose such that dispose listeners get a change to react
         this._onDispose.fire();
         super.dispose();