It would really help if you provided the commands that you’ve inserted in your build script. From what I can see in a glance, this line that you posted seems questionable:
/bigblockengine/mods: not a directory
From what I can tell, you passed “/bigblockengine/mods” as a parameter, which is an Absolute Path, not a Relative Path. That means it’s not looking for it in the current directory (which would look something like “/home/<your_username>/<path_to_your_project/bigblockengine/mods”), but it’s instead looking for it at “/bigblockengine/mods”.
This would be fixed if you removed the first slash and it became “bigblockengine/mods”, so that it will look for that folder locally. But unless you post the command that your script is using, I can’t guarantee this is the solution, this is the only thing I saw that could have caused it.