Main Thread Checker: UI API called on a background thread: -[UIView setSize:]

Main Thread Checker: UI API called on a background thread: -[UIView setSize:]
PID: 781, TID: 78231, Thread name: (none), Queue name: org.webrtc.cameravideocapturer.video, QoS: 25
Backtrace:
4 WebRTC 0x0000000107929a68 RTCShutdownInternalTracer + 5443932
5 WebRTC 0x000000010743ed0c RTCShutdownInternalTracer + 287744
6 WebRTC 0x000000010743abf4 RTCShutdownInternalTracer + 271080
7 WebRTC 0x00000001073e1230 RTCFileName + 30928
8 WebRTC 0x0000000107929e98 RTCShutdownInternalTracer + 5445004
9 WebRTC 0x00000001073fa6c8 RTCShutdownInternalTracer + 7612
10 AVFCapture 0x00000001b1f3ac30 7A9D2EB5-0A39-38D2-9FF1-1C8035FA7EBA + 113712
11 AVFCapture 0x00000001b1f3aafc 7A9D2EB5-0A39-38D2-9FF1-1C8035FA7EBA + 113404
12 CMCapture 0x00000001b56f02e4 DB0E358C-AA45-34A4-8765-2B536E5CDF99 + 275172
13 CMCapture 0x00000001b56f0220 DB0E358C-AA45-34A4-8765-2B536E5CDF99 + 274976
14 libdispatch.dylib 0x00000001063ea7bc _dispatch_client_callout + 20
15 libdispatch.dylib 0x00000001063ed8e0 _dispatch_continuation_pop + 676
16 libdispatch.dylib 0x0000000106404cc8 _dispatch_source_latch_and_call + 480
17 libdispatch.dylib 0x0000000106403718 _dispatch_source_invoke + 860
18 libdispatch.dylib 0x00000001063f24a4 _dispatch_lane_serial_drain + 376
19 libdispatch.dylib 0x00000001063f3408 _dispatch_lane_invoke + 408
20 libdispatch.dylib 0x0000000106400404 _dispatch_root_queue_drain_deferred_wlh + 328
21 libdispatch.dylib 0x00000001063ffa38 _dispatch_workloop_worker_thread + 444
22 libsystem_pthread.dylib 0x00000001f1010f20 _pthread_wqthread + 288
23 libsystem_pthread.dylib 0x00000001f1010fc0 start_wqthread + 8
Main Thread Checker: UI API called on a background thread: -[UIView setSize:]
PID: 781, TID: 78231, Thread name: (none), Queue name: org.webrtc.cameravideocapturer.video, QoS: 25
Backtrace:
4 WebRTC 0x0000000107929a68 RTCShutdownInternalTracer + 5443932
5 WebRTC 0x000000010743ed0c RTCShutdownInternalTracer + 287744
6 WebRTC 0x000000010743abf4 RTCShutdownInternalTracer + 271080
7 WebRTC 0x00000001073e1230 RTCFileName + 30928
8 WebRTC 0x0000000107929e98 RTCShutdownInternalTracer + 5445004
9 WebRTC 0x00000001073fa6c8 RTCShutdownInternalTracer + 7612
10 AVFCapture 0x00000001b1f3ac30 7A9D2EB5-0A39-38D2-9FF1-1C8035FA7EBA + 113712
11 AVFCapture 0x00000001b1f3aafc 7A9D2EB5-0A39-38D2-9FF1-1C8035FA7EBA + 113404
12 CMCapture 0x00000001b56f02e4 DB0E358C-AA45-34A4-8765-2B536E5CDF99 + 275172
13 CMCapture 0x00000001b56f0220 DB0E358C-AA45-34A4-8765-2B536E5CDF99 + 274976
14 libdispatch.dylib 0x00000001063ea7bc _dispatch_client_callout + 20
15 libdispatch.dylib 0x00000001063ed8e0 _dispatch_continuation_pop + 676
16 libdispatch.dylib 0x0000000106404cc8 _dispatch_source_latch_and_call + 480
17 libdispatch.dylib 0x0000000106403718 _dispatch_source_invoke + 860
18 libdispatch.dylib 0x00000001063f24a4 _dispatch_lane_serial_drain + 376
19 libdispatch.dylib 0x00000001063f3408 _dispatch_lane_invoke + 408
20 libdispatch.dylib 0x0000000106400404 _dispatch_root_queue_drain_deferred_wlh + 328
21 libdispatch.dylib 0x00000001063ffa38 _dispatch_workloop_worker_thread + 444
22 libsystem_pthread.dylib 0x00000001f1010f20 _pthread_wqthread + 288
23 libsystem_pthread.dylib 0x00000001f1010fc0 start_wqthread + 8
*** Terminating app due to uncaught exception ‘NSInvalidArgumentException’, reason: ‘-[UIView renderFrame:]: unrecognized selector sent to instance 0x15df799c0’
*** First throw call stack:
(0x19511ab28 0x18cf92f78 0x1951abeec 0x1980fb44c 0x195060300 0x1951a1760 0x107929ab4 0x10743ed0c 0x10743abf4 0x1073e1230 0x107929e98 0x1073fa6c8 0x1b1f3ac30 0x1b1f3aafc 0x1b56f02e4 0x1b56f0220 0x1063ea7bc 0x1063ed8e0 0x106404cc8 0x106403718 0x1063f24a4 0x1063f3408 0x106400404 0x1063ffa38 0x1f1010f20 0x1f1010fc0)
libc++abi: terminating due to uncaught exception of type NSException
Hi guys, what might be the problem here? I still can’t figure out. I would be thankful if you help me guys!
I got this demo example from this github account