also ignore stale *failed* responses - #741

since `misskeyApi` doesn't pass us the request, we close over a copy
of the username we requested, to make sure it still matches the
current username value

packages/frontend/src/components/MkSignin.vue

@@ -107,14 +107,17 @@ const props = withDefaults(defineProps<{
 });
 
 function onUsernameChange(): void {
+	const usernameRequested = username.value;
 	misskeyApi('users/show', {
-		username: username.value,
+		username: usernameRequested,
 	}).then(userResponse => {
 		if (userResponse.username === username.value) {
 			user.value = userResponse;
 		}
 	}, () => {
+		if (usernameRequested === username.value) {
 			user.value = null;
+		}
 	});
 }