Finally got the error with the debug build.
instrument.js:102 [mb_enhanced_cover_art_uploads] Searching for images in Apple Music release…
instrument.js:102 Response finalUrl is undefined
instrument.js:102 Response is {"responseHeaders":null,"readyState":4,"status":200,"statusText":"","lengthComputable":false,"loaded":413040,"total":0,"response":null,"responseText":null}
instrument.js:102 [mb_enhanced_cover_art_uploads] Failed to fetch or enqueue images TypeError: Failed to construct 'URL': Invalid URL
at MB: Enhanced Cover Art Uploads.user.js:106220:72
(anonymous) @ instrument.js:102
https://musicbrainz.org/release/561e8a53-bd69-4609-ac6e-01b87a04b6c1/add-cover-art?x_seed.image.0.url=https%3A%2F%2Fmusic.apple.com%2Fgb%2Falbum%2F1582667542&x_seed.origin=https%3A%2F%2Fatisket.pulsewidth.org.uk%2F%3Fcached%3D00602438517848-d_0-s_0bztigq9w8sLg2nHdmq4Td-i_1582667542
Another one:
instrument.js:102 [mb_enhanced_cover_art_uploads] Fetching https://mikehuguenor.bandcamp.com/album/the-gateless-gate
instrument.js:102 [mb_enhanced_cover_art_uploads] Searching for images in Bandcamp release…
instrument.js:102 Response finalUrl is https://mikehuguenor.bandcamp.com/album/the-gateless-gate
instrument.js:102 Response is {"finalUrl":"https://mikehuguenor.bandcamp.com/album/the-gateless-gate","responseHeaders":null,"readyState":4,"status":200,"statusText":"OK","lengthComputable":false,"loaded":177341,"total":0,"response":null,"responseText":null}
instrument.js:102 [mb_enhanced_cover_art_uploads] Checking for Bandcamp track images, this may take a few seconds…
instrument.js:102 Response finalUrl is https://mikehuguenor.bandcamp.com/track/the-gateless-gate
instrument.js:102 Response is {"finalUrl":"https://mikehuguenor.bandcamp.com/track/the-gateless-gate","responseHeaders":null,"readyState":4,"status":200,"statusText":"OK","lengthComputable":false,"loaded":144784,"total":0,"response":null,"responseText":null}
instrument.js:102 [mb_enhanced_cover_art_uploads] Checking for Bandcamp track images, this may take a few seconds… (1/2)
instrument.js:102 Response finalUrl is https://mikehuguenor.bandcamp.com/track/mumons-commentary
instrument.js:102 Response is {"finalUrl":"https://mikehuguenor.bandcamp.com/track/mumons-commentary","responseHeaders":null,"readyState":4,"status":200,"statusText":"OK","lengthComputable":false,"loaded":144847,"total":0,"response":null,"responseText":null}
instrument.js:102 [mb_enhanced_cover_art_uploads] Checking for Bandcamp track images, this may take a few seconds… (2/2)
instrument.js:102 [mb_enhanced_cover_art_uploads] Found no unique track images this time
instrument.js:102 [mb_enhanced_cover_art_uploads] Getting image dimensions for https://f4.bcbits.com/img/a3563316698_0.jpg
instrument.js:102 [mb_enhanced_cover_art_uploads] Found 1 image(s) in Bandcamp release
instrument.js:102 [mb_enhanced_cover_art_uploads] Fetching https://f4.bcbits.com/img/a3563316698_10.jpg (1/1)
instrument.js:102 Response finalUrl is undefined
instrument.js:102 Response is {"readyState":4,"status":200,"statusText":"","lengthComputable":true,"loaded":8958943,"total":8958943,"response":null,"responseHeaders":null,"responseText":null}
instrument.js:102 [mb_enhanced_cover_art_uploads] Skipping maximised candidate https://f4.bcbits.com/img/a3563316698_0.jpg TypeError: Failed to construct 'URL': Invalid URL
at MB: Enhanced Cover Art Uploads.user.js:110528:30
(anonymous) @ instrument.js:102
instrument.js:102 Response finalUrl is https://f4.bcbits.com/img/a3563316698_10.jpg
instrument.js:102 Response is {"finalUrl":"https://f4.bcbits.com/img/a3563316698_10.jpg","readyState":4,"status":200,"statusText":"","lengthComputable":true,"loaded":335879,"total":335879,"response":null,"responseHeaders":null,"responseText":null}
instrument.js:102 [mb_enhanced_cover_art_uploads] Successfully added 1 image(s)
https://musicbrainz.org/release/8f6c79b7-4603-422b-bd21-5fa9a58316fd
Violentmonkey BETA 2.13.0.22
Google Chrome 103.0.5060.132