Conform more code to strict null checking (#10169)

* Conform more code to strict null checking

* delint

* Iterate

* delint

* Fix bad test

src/components/views/user-onboarding/UserOnboardingButton.tsx

@@ -39,7 +39,7 @@ export function UserOnboardingButton({ selected, minimized }: Props): JSX.Elemen
     const visible = useSettingValue<boolean>("FTUE.userOnboardingButton");
 
     if (!visible || minimized || !showUserOnboardingPage(useCase)) {
-        return null;
+        return <></>;
     }
 
     return <UserOnboardingButtonInternal selected={selected} minimized={minimized} />;

src/components/views/user-onboarding/UserOnboardingFeedback.tsx

@@ -26,7 +26,7 @@ import { shouldShowFeedback } from "../../../utils/Feedback";
 
 export function UserOnboardingFeedback(): JSX.Element {
     if (!shouldShowFeedback()) {
-        return null;
+        return <></>;
     }
 
     return (

src/components/views/user-onboarding/UserOnboardingTask.tsx

@@ -57,7 +57,7 @@ export function UserOnboardingTask({ task, completed = false }: Props): JSX.Elem
                     kind="primary_outline"
                     href={task.action.href}
                     target="_blank"
-                    onClick={task.action.onClick}
+                    onClick={task.action.onClick ?? null}
                 >
                     {task.action.label}
                 </AccessibleButton>