chore: remove superfluous code

Author: philippfromme

lib/TaskExecution.js

@@ -51,9 +51,6 @@ export default class TaskExecution extends EventEmitter {
   constructor(injector, api) {
     super();
 
-    /** @type {import('didi').Injector} */
-    this._injector = injector;
-
     /** @type {TaskExecutionApi} */
     this._api = api;