fix: eliminate JSX.Element from generated typings

Either add JSDoc or TypeScript annotations so that `Mithril.Children` is always returned in favor of `JSX.Element`.

extensions/package-manager/js/src/admin/components/Updater.tsx

@@ -64,7 +64,7 @@ export default class Updater<Attrs> extends Component<Attrs> {
     super.oninit(vnode);
   }
 
-  view() {
+  view(): Mithril.Children {
     const extensions = this.getExtensionUpdates();
     let coreUpdate: UpdatedPackage | undefined = this.getCoreUpdate();
     let core: any;

extensions/package-manager/js/src/admin/components/WhyNotModal.tsx

@@ -26,7 +26,7 @@ export default class WhyNotModal<Attrs extends WhyNotModalAttrs = WhyNotModalAtt
     this.requestWhyNot();
   }
 
-  content() {
+  content(): Mithril.Children {
     return <div className="Modal-body">{this.loading ? <LoadingIndicator /> : <pre className="WhyNotModal-contents">{this.whyNot}</pre>}</div>;
   }