ffmpeg direct merger audio and video

Directly running the FFmpeg command shown in Youtube-DL log resulted in an error message, with exit code 1:

C>ffmpeg -y -loglevel "repeat+info" -i "file:ueoRSzCn4kA.480p+m4a128k.f135.mp4" -i "file:ueoRSzCn4kA.480p+m4a128k.mp4.f140" -c copy -map "0:v:0" -map "1:a:0" "file:ueoRSzCn4kA.480p+m4a128k.temp.mp4"
Invalid loglevel "repeat+info". Possible levels are numbers or:
"quiet"
"panic"
"fatal"
"error"
"warning"
"info"
"verbose"
"debug"

C>echo %ERRORLEVEL%
1

Running the same FFmpeg command line, without the problematic -loglevel "repeat+info" part, resulted in a successful remux and a watchable file; the remuxer also exited with code 0:

C>ffmpeg -y -i "file:ueoRSzCn4kA.480p+m4a128k.f135.mp4" -i "file:ueoRSzCn4kA.480p+m4a128k.mp4.f140" -c copy -map "0:v:0" -map "1:a:0" "file:ueoRSzCn4kA.480p+m4a128k.temp.mp4"
...
frame=36452 fps=464 q=-1.0 size=  142867kB time=00:24:16.10 bitrate= 803.8kbits/s
frame=36452 fps=464 q=-1.0 Lsize=  144068kB time=00:24:18.14 bitrate= 809.4kbits/s
video:120143kB audio:22783kB subtitle:0 global headers:0kB muxing overhead 0.798212%

C>echo %ERRORLEVEL%
0