Process is not defined

Hi there,
I need some help so, I clone this repo and run but I got error as below
```
createFFmpeg.js:167 Uncaught (in promise) Error: Oops, something went wrong in FS operation.
at Object.FS (createFFmpeg.js:167:1)
at doTranscode (App.js:15:1)
FS @ createFFmpeg.js:167
doTranscode @ App.js:15
await in doTranscode (async)
callCallback @ react-dom.development.js:188
invokeGuardedCallbackDev @ react-dom.development.js:237
invokeGuardedCallback @ react-dom.development.js:292
invokeGuardedCallbackAndCatchFirstError @ react-dom.development.js:306
executeDispatch @ react-dom.development.js:389
executeDispatchesInOrder @ react-dom.development.js:414
executeDispatchesAndRelease @ react-dom.development.js:3278
executeDispatchesAndReleaseTopLevel @ react-dom.development.js:3287
forEachAccumulated @ react-dom.development.js:3259
runEventsInBatch @ react-dom.development.js:3304
runExtractedPluginEventsInBatch @ react-dom.development.js:3514
handleTopLevel @ react-dom.development.js:3558
batchedEventUpdates$1 @ react-dom.development.js:21871
batchedEventUpdates @ react-dom.development.js:795
dispatchEventForLegacyPluginEventSystem @ react-dom.development.js:3568
attemptToDispatchEvent @ react-dom.development.js:4267
dispatchEvent @ react-dom.development.js:4189
unstable_runWithPriority @ scheduler.development.js:653
runWithPriority$1 @ react-dom.development.js:11039
discreteUpdates$1 @ react-dom.development.js:21887
discreteUpdates @ react-dom.development.js:806
dispatchDiscreteEvent @ react-dom.development.js:4168
VM10:2 Uncaught ReferenceError: process is not defined
at Object.4043 (:2:13168)
at r (:2:306599)
at Object.8048 (:2:9496)
at r (:2:306599)
at Object.8641 (:2:1379)
at r (:2:306599)
at :2:315627
at :2:324225
at :2:324229
at HTMLIFrameElement.e.onload (index.js:1:1)
```

this should not exist on browser, right?