MaCarte unable to load a .carte file on Firefox

[loopfinito]

A user reported by mail that he was unable to load symboles-panneaux.carte on Firefox, the follwing error appeared with the dev tools

Uncaught SyntaxError: JSON.parse: unexpected non-whitespace character after JSON data at line 32771 column 2 of the JSON data
onload https://macarte.ign.fr/edition/carte/src.6a66a5b4.js:1670
l https://macarte.ign.fr/edition/carte/src.6a66a5b4.js:1670
s https://macarte.ign.fr/edition/carte/src.6a66a5b4.js:1688
s https://macarte.ign.fr/edition/carte/src.6a66a5b4.js:1688
NeeO https://macarte.ign.fr/edition/carte/src.6a66a5b4.js:1688
setTimeout handler*parcelRequire<.NeeO</< https://macarte.ign.fr/edition/carte/src.6a66a5b4.js:1688
src.6a66a5b4.js:1670:733
onload https://macarte.ign.fr/edition/carte/src.6a66a5b4.js:1670
(Asynchrone : EventHandlerNonNull)
l https://macarte.ign.fr/edition/carte/src.6a66a5b4.js:1670
s https://macarte.ign.fr/edition/carte/src.6a66a5b4.js:1688
forEach self-hosted:164
s https://macarte.ign.fr/edition/carte/src.6a66a5b4.js:1688
NeeO https://macarte.ign.fr/edition/carte/src.6a66a5b4.js:1688
(Asynchrone : setTimeout handler)
NeeO https://macarte.ign.fr/edition/carte/src.6a66a5b4.js:1688

Thank you

[Viglino]

I think the issue is in the map file you're trying to load.
It must be a valid json.
Try to test it with a json validator.