Well, first of all, when the error pops up, the window ussually says:
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RTE Aborted! (x_x)
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Could not match property Error happened in ____.rte/Weapons/____.ini at line _!
The last frame has been dumped to 'abortscreen.bmp'
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Before you do close it, go to the ini file, and go to which line it says, and see whats the problem is, but if nothings wrong with it, I suggest comparing it to other SMG files to see what's missing.
(Atleast thats all what I can say, Lol)