Allow changing server if validation has failed

Show the server config section if there's an error and fix an if
case where we forgot to un-set the busy flag

src/components/views/auth/ServerConfig.js

@@ -104,6 +104,9 @@ export default class ServerConfig extends React.PureComponent {
 
             const stateForError = AutoDiscoveryUtils.authComponentStateForError(e);
             if (!stateForError.isFatalError) {
+                this.setState({
+                    busy: false,
+                });
                 // carry on anyway
                 const result = await AutoDiscoveryUtils.validateServerConfigWithStaticUrls(hsUrl, isUrl, true);
                 this.props.onServerConfigChange(result);