code quality improvements and improved file error handling

src/hooks/useOverviewVideo.ts

@@ -2,8 +2,6 @@ import { useQuery } from "@tanstack/react-query";
 import { useRef } from "react";
 
 const apiUrl = import.meta.env.VITE_BASEURL;
-const FAST_MS = 200; // tab visible
-const SLOW_MS = 2000; // tab hidden
 
 async function fetchOverviewImage(cameraSide: string) {
   const response = await fetch(`${apiUrl}${cameraSide}-preview`);