From c1a4724e992e9a5bdedb8c7dd060c85ee6fe8996 Mon Sep 17 00:00:00 2001
From: Matthew Stratford <hi@mstratford.net>
Date: Sat, 30 Jan 2021 19:13:04 +0000
Subject: [PATCH] Fix PFL VU meter trying to update after it's killed.

---
 src/optionsMenu/helpers/VUMeter.tsx | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/optionsMenu/helpers/VUMeter.tsx b/src/optionsMenu/helpers/VUMeter.tsx
index 0e7791b..c20bc13 100644
--- a/src/optionsMenu/helpers/VUMeter.tsx
+++ b/src/optionsMenu/helpers/VUMeter.tsx
@@ -30,18 +30,19 @@ export function VUMeter(props: VUMeterProps) {
   const FPS = 30; // Limit the FPS so that lower spec machines have a better time juggling CPU.
 
   useEffect(() => {
+    let isMounted = true; // This VU exists as we're calling useEffect
     const animate = () => {
-      if (!isMic || isMicOpen) {
+      if ((!isMic || isMicOpen) && isMounted) {
         const result = audioEngine.getLevels(
           props.source,
           props.stereo ? props.stereo : false
         );
         setPeakL(result[0]);
-        if (props.stereo) {
+        if (props.stereo && isMounted) {
           setPeakR(result[1]);
         }
         setTimeout((current = rafRef.current, a = animate) => {
-          current = requestAnimationFrame(a);
+          if (isMounted) current = requestAnimationFrame(a);
         }, 1000 / FPS);
       }
     };
@@ -49,6 +50,7 @@ export function VUMeter(props: VUMeterProps) {
       rafRef.current = requestAnimationFrame(animate);
     }
     return () => {
+      isMounted = false; // Tell the async stuff above to not bother if the VU meter has gone away.
       if (rafRef.current !== null) {
         cancelAnimationFrame(rafRef.current);
         rafRef.current = null;