Disable list title validation button when list title is empty (mastodon#11475)

Author: ClearlyClaire

app/javascript/mastodon/features/list_editor/components/edit_list_form.js

@@ -11,7 +11,7 @@ const messages = defineMessages({
 
 const mapStateToProps = state => ({
   value: state.getIn(['listEditor', 'title']),
-  disabled: !state.getIn(['listEditor', 'isChanged']),
+  disabled: !state.getIn(['listEditor', 'isChanged']) || !state.getIn(['listEditor', 'title']),
 });
 
 const mapDispatchToProps = dispatch => ({

app/javascript/mastodon/features/lists/components/new_list_form.js

@@ -66,7 +66,7 @@ class NewListForm extends React.PureComponent {
         </label>
 
         <IconButton
-          disabled={disabled}
+          disabled={disabled || !value}
           icon='plus'
           title={title}
           onClick={this.handleClick}