Fix crash in /web/lists

Fixes #1181

app/javascript/flavours/glitch/features/lists/index.js

@@ -57,6 +57,8 @@ export default class Lists extends ImmutablePureComponent {
       );
     }
 
+    const emptyMessage = <FormattedMessage id='empty_column.lists' defaultMessage="You don't have any lists yet. When you create one, it will show up here." />;
+
     return (
       <Column icon='bars' heading={intl.formatMessage(messages.heading)}>
         <ColumnBackButtonSlim />