Batch-add "performance of" relationships error

[dmromanov]

The Batch-add "performance of" relationships script fails to initialize correctly on some pages. E.g. https://musicbrainz.org/artist/067f26c1-d678-410e-8217-e554a3418143/recordings?filter.artist_credit_id=%C2%A0&filter.name=cafe&page=2 https://musicbrainz.org/artist/70cb4669-ad7a-4d5c-b99e-7582df393cc7/recordings?filter.artist_credit_id=%C2%A0&filter.name=informer

Uncaught TypeError: Cannot read property '1' of null
    at batch_recording_rels (<anonymous>:434:74)
    at <anonymous>:1295:3
    at Window.tms_56d0ee97_9554_4447_bc40_e0ce97b64219 (chrome-extension://dhdgffkkebhmkfjojejmpbldmpobfkfo/userscript.html?id=56d0ee97-9554-4447-bc40-e0ce97b64219:49:15)
    at <anonymous>:2:120
    at eval (chrome-extension://dhdgffkkebhmkfjojejmpbldmpobfkfo/userscript.html?id=56d0ee97-9554-4447-bc40-e0ce97b64219:3:1)
    at eval (chrome-extension://dhdgffkkebhmkfjojejmpbldmpobfkfo/userscript.html?id=56d0ee97-9554-4447-bc40-e0ce97b64219:4:3)
    at Object.eval (chrome-extension://dhdgffkkebhmkfjojejmpbldmpobfkfo/userscript.html?id=56d0ee97-9554-4447-bc40-e0ce97b64219:1347:6)
    at <anonymous>:2:120
    at Object.E_c (<anonymous>:2:433)
    at oa (eval at exec_fn (:1:108), <anonymous>:60:203)
    at Object.create (eval at exec_fn (:1:108), <anonymous>:71:116)
    at e (eval at exec_fn (:1:108), <anonymous>:15:131)

[psychoadept]

Not sure if this is related, but I notice that when the recording list is filtered, it fails to identify works that are already attached, which can lead to duplicates being added.