Turn on noUnusedLocals, noImplicitReturns, importsNotUsedAsValues: error, and isolatedModules (#2777)

src/renderer/components/layout/main-layout-header.tsx

@@ -21,7 +21,7 @@
 
 import React from "react";
 import { observer } from "mobx-react";
-import { Cluster } from "../../../main/cluster";
+import type { Cluster } from "../../../main/cluster";
 import { cssNames } from "../../utils";
 
 interface Props {

src/renderer/components/layout/sidebar-item.tsx

@@ -88,7 +88,7 @@ export class SidebarItem extends React.Component<SidebarItemProps> {
     const { isExpandable, expanded, isActive } = this;
 
     if (!isExpandable || !expanded) {
-      return;
+      return null;
     }
 
     return (

src/renderer/components/layout/sidebar.tsx

@@ -155,7 +155,7 @@ export class Sidebar extends React.Component<Props> {
         pageUrl = tabRoutes[0].url;
         isActive = isActiveRoute(tabRoutes.map((tab) => tab.routePath));
       } else {
-        return;
+        return null;
       }
 
       return (