... and take action when the counter reaches zero in verification toast

src/components/views/toasts/VerificationRequestToast.js

@@ -38,6 +38,11 @@ export default class VerificationRequestToast extends React.PureComponent {
                 let {counter} = this.state;
                 counter = Math.max(0, counter - 1);
                 this.setState({counter});
+
+                if (counter == 0) {
+                    clearInterval(this._intervalHandle);
+                    this.cancel();
+                }
             }, 1000);
         }
         request.on("change", this._checkRequestIsPending);