Fixing persisting error message from MobileSyncPage (#11835)

ui/pages/mobile-sync/mobile-sync.component.js

@@ -28,6 +28,7 @@ export default class MobileSyncPage extends Component {
     requestRevealSeedWords: PropTypes.func.isRequired,
     exportAccounts: PropTypes.func.isRequired,
     keyrings: PropTypes.array,
+    hideWarning: PropTypes.func.isRequired,
   };
 
   state = {
@@ -277,6 +278,9 @@ export default class MobileSyncPage extends Component {
   }
 
   componentWillUnmount() {
+    if (this.state.error) {
+      this.props.hideWarning();
+    }
     this.clearTimeouts();
     this.disconnectWebsockets();
   }

ui/pages/mobile-sync/mobile-sync.container.js

@@ -4,6 +4,7 @@ import {
   requestRevealSeedWords,
   fetchInfoToSync,
   exportAccounts,
+  hideWarning,
 } from '../../store/actions';
 import { getMostRecentOverviewPage } from '../../ducks/history/history';
 import { getMetaMaskKeyrings } from '../../selectors';
@@ -17,6 +18,7 @@ const mapDispatchToProps = (dispatch) => {
     displayWarning: (message) => dispatch(displayWarning(message || null)),
     exportAccounts: (password, addresses) =>
       dispatch(exportAccounts(password, addresses)),
+    hideWarning: () => dispatch(hideWarning()),
   };
 };