content: Missing clean-up function in useEffect to remove event listener.

[decipher-cs]

URL

https://ionicframework.com/docs/theming/dark-mode#css-class

Issue Description

The example in src/main.tsx for setting dark mode doesn't use a clean-up function inside the useEffect when adding event listener.

useEffect(() => {
 // Listen for changes to the prefers-color-scheme media query
 prefersDark.addEventListener('change', (mediaQuery) => initializeDarkPalette(mediaQuery.matches));
 }, []);

This would just continuously add listeners.

This would fix the issue.

useEffect(() => {
 // Listen for changes to the prefers-color-scheme media query
 prefersDark.addEventListener('change', funct);
 return ()=>{
 prefersDark.removeEventListener('change', funct);
 }
 }, []);