If you change files in game's program folder, that means clean reinstall is in order. Always add stuff to documents folder instead. If you have not messed files in program folder, then disable mods, remove everything from documents beamng vehicles.
Seems to be a problem in the Jbeam itself, no reason to reinstall the game (yet). Make sure the Jbeam is valid, you might be missing a simple comma or bracket somewhere.
Sometimes it can get bit confusing, error can be completely different file than it complains, only way is to very carefully go trough whole file then. However you did say you did remove what you added, so if you don't have added files, then it would look more of issue with ingame files. However if you just removed what you added from the file, you might have on extra or missing } Also common errors are: O instead of 0 .0 instead of 0.0 '' or `` instead of " no, I'm not pulling your leg here, first is two of ' instead of quotation mark " and `` is two ` Your error says error comparing number to nil, that means nothing while it was excepting a number it found nothing. Reasons for that can be mistyped number like .0 for example, or as it is saying partMap, that could be that there is error which prevents list of parts to be loaded, like missing " or { Attaching file you have edited to your message would allow us to look for some common issues, but it really is just counting all { and } one by one, as well as checking numbers are numbers and quotation marks are at place. Sometimes it is easier to make new file, copy paste wanted section and check if there is all { etc. in place. Then there are some characters that don't really show up much, something like ´ on some keyboards, you press one key which does nothing, then press another key and that symbol appears, note ´ and ` are again different.
