fix(FEC-11492): dash adapter is not destroyed when network is offline (…

…#167)

**issue:**
once dash is triggering critical error event, we are not destroying the engine.

**solution:**
destroying engine when critical event is being fired.

Solves FEC-11492

src/dash-adapter.js

@@ -1214,6 +1214,9 @@ export default class DashAdapter extends BaseMediaSourceAdapter {
       }
       this._trigger(EventType.ERROR, new Error(error.severity, error.category, error.code, error.data));
       DashAdapter._logger.error(error);
+      if (error.severity === Error.Severity.CRITICAL) {
+        this.destroy();
+      }
     }
   }