improve error message on startup #1114

src/App.jsx

@@ -56,6 +56,7 @@ import {
   extractStreams, runStartupCheck, setCustomFfPath as ffmpegSetCustomFfPath,
   isIphoneHevc, tryMapChaptersToEdl, blackDetect,
   getDuration, getTimecodeFromStreams, createChaptersFromSegments, extractSubtitleTrack,
+  getFfmpegPath,
 } from './ffmpeg';
 import { shouldCopyStreamByDefault, getAudioStreams, getRealVideoStreams, defaultProcessedCodecTypes, isAudioDefinitelyNotSupported, doesPlayerSupportFile } from './util/streams';
 import { exportEdlFile, readEdlFile, saveLlcProject, loadLlcProject, askForEdlImport } from './edlStore';
@@ -2272,7 +2273,24 @@ const App = memo(() => {
 
   const haveCustomFfPath = !!customFfPath;
   useEffect(() => {
-    if (!haveCustomFfPath) runStartupCheck().catch((err) => handleError('LosslessCut is installation is broken', err));
+    if (!haveCustomFfPath) {
+      (async () => {
+        try {
+          await runStartupCheck();
+        } catch (err) {
+          if (['EPERM', 'EACCES'].includes(err.code)) {
+            toast.fire({
+              timer: 30000,
+              icon: 'error',
+              title: 'Fatal: ffmpeg not accessible',
+              text: `Got ${err.code}. This probably means that anti-virus is blocking execution of ffmpeg. Please make sure the following file exists and is executable:\n\n${getFfmpegPath()}\n\nSee this issue: https://github.com/mifi/lossless-cut/issues/1114`,
+            });
+            return;
+          }
+          handleError('Fatal: ffmpeg non-functional', err);
+        }
+      })();
+    }
   }, [haveCustomFfPath]);
 
   useEffect(() => {

src/util.js

@@ -116,7 +116,7 @@ export function handleError(arg1, arg2) {
   toast.fire({
     icon: 'error',
     title: msg || i18n.t('An error has occurred.'),
-    text: errorMsg ? errorMsg.substr(0, 300) : undefined,
+    text: errorMsg ? errorMsg.substring(0, 300) : undefined,
   });
 }