I think the others have taken care of the basic problems in your code. Just one more little nit-pick about how you present the problem...

You quote a warning message that cites line 48 in your code, but the code you posted has less than 35 lines total. So we have to assume that there is some code you haven't shown us, and that by itself is not a bad thing -- you've posted the relevant parts, which is good.

It would have helped to add a comment on the line that had originally been line #48 so that it's obvious where the error/warning message came from, and maybe even add a comment to say "# removed some irrelevant stuff from here...", just to eliminate any confusion about what you're showing us.