From f70f91a6f8dc5617461d1abcc64374d713dbdd56 Mon Sep 17 00:00:00 2001
From: Jerome Wu <jeromewus@gmail.com>
Date: Sat, 24 Jul 2021 17:16:10 +0800
Subject: [PATCH] Enhance error message

---
 src/browser/getCreateFFmpegCore.js |  6 ++++++
 src/utils/errors.js                | 11 +++++++++++
 2 files changed, 17 insertions(+)
 create mode 100644 src/utils/errors.js

diff --git a/src/browser/getCreateFFmpegCore.js b/src/browser/getCreateFFmpegCore.js
index ed38e0b..f31167e 100644
--- a/src/browser/getCreateFFmpegCore.js
+++ b/src/browser/getCreateFFmpegCore.js
@@ -1,6 +1,9 @@
 /* eslint-disable no-undef */
 const resolveURL = require('resolve-url');
 const { log } = require('../utils/log');
+const {
+  CREATE_FFMPEG_CORE_IS_NOT_DEFINED,
+} = require('../utils/errors');
 
 /*
  * Fetch data from remote URL and convert to blob URL
@@ -38,6 +41,9 @@ module.exports = async ({ corePath: _corePath }) => {
       const script = document.createElement('script');
       const eventHandler = () => {
         script.removeEventListener('load', eventHandler);
+        if (typeof createFFmpegCore === 'undefined') {
+          throw Error(CREATE_FFMPEG_CORE_IS_NOT_DEFINED(coreRemotePath));
+        }
         log('info', 'ffmpeg-core.js script loaded');
         resolve({
           createFFmpegCore,
diff --git a/src/utils/errors.js b/src/utils/errors.js
new file mode 100644
index 0000000..58a0c77
--- /dev/null
+++ b/src/utils/errors.js
@@ -0,0 +1,11 @@
+const CREATE_FFMPEG_CORE_IS_NOT_DEFINED = (corePath) => (`
+createFFmpegCore is not defined. ffmpeg.wasm is unable to find createFFmpegCore after loading ffmpeg-core.js from ${corePath}. Use another URL when calling createFFmpeg():
+
+const ffmpeg = createFFmpeg({
+  corePath: 'http://localhost:3000/ffmpeg-core.js',
+});
+`);
+
+module.exports = {
+  CREATE_FFMPEG_CORE_IS_NOT_DEFINED,
+};