GUI: Fix crashing when attempting to read config (fixes #505)
GUI: Fix crashing when attempting to read config (fixes #505)

sergiobenrocha2/mgba,sergiobenrocha2/mgba,libretro/mgba,jeremyherbert/mgba,Iniquitatis/mgba,Iniquitatis/mgba,Anty-Lemon/mgba,libretro/mgba,Iniquitatis/mgba,fr500/mgba,sergiobenrocha2/mgba,libretro/mgba,mgba-emu/mgba,Anty-Lemon/mgba,jeremyherbert/mgba,sergiobenrocha2/mgba,mgba-emu/mgba,fr500/mgba,libretro/mgba,fr500/mgba,Anty-Lemon/mgba,mgba-emu/mgba,Iniquitatis/mgba,jeremyherbert/mgba,sergiobenrocha2/mgba,libretro/mgba,fr500/mgba,mgba-emu/mgba,jeremyherbert/mgba,Anty-Lemon/mgba