fix warning about no key being set for settings category list

ts/components/session/LeftPaneSettingSection.tsx

@@ -30,7 +30,6 @@ export class LeftPaneSettingSection extends React.Component<any, State> {
     };
 
     this.setCategory = this.setCategory.bind(this);
-    this.renderRows = this.renderRows.bind(this);
   }
 
   public componentDidMount() {
@@ -62,14 +61,8 @@ export class LeftPaneSettingSection extends React.Component<any, State> {
     );
   }
 
-  public renderRows(): JSX.Element {
+  public renderRow(item: any): JSX.Element {
-    const categories = this.getCategories();
-
     return (
-      <>
-        {categories.map(item => (
-          <>
-            {!item.hidden && (
       <div
         key={item.id}
         className={classNames(
@@ -97,18 +90,16 @@ export class LeftPaneSettingSection extends React.Component<any, State> {
           )}
         </div>
       </div>
-            )}
-          </>
-        ))}
-      </>
     );
   }
 
   public renderCategories(): JSX.Element {
+    const categories = this.getCategories().filter(item => !item.hidden);
+
     return (
       <div className="module-left-pane__list" key={0}>
         <div className="left-pane-setting-category-list">
-          {this.renderRows()}
+          {categories.map(item => this.renderRow(item))};
         </div>
       </div>
     );