I don't know if this "problem" is known or not but I think it's not a waste of time to report it.
I noticed by chance that if you have more than one plugins in your vsh.txt or game.txt ( i don't know if this happens also in the pops.txt because I never used it) and if you try to delete THE LAST line using the comand "remove prx", it will show :
"Error: ?:0: attempt to index field '?' < a nil value>
Press start to restart"
For example if you have :
If you try to delete the last) line by using "Remove prx" the error will show up.
The same happens in game.txt if you have more line and you want to delete the last one.
However I find a temporary solutions to this problem that is: if you move up the last line that you want to delete using the comand "Move PRX Up" or just move it in a way that the line you want to delete isn't the last one and then you delete the line that you just moved, the program will delete it and will not show the error.
This problem is not a great deal, but if you can fix it, it will be really perfect (at least for me
I have tried quite different plugins manager but I prefer yours the most.