pktools/lib/gba.py: Improved error and message handling for gba
pktools/lib/gba.py: Improved error and message handling for gba

Added more specific error messages for gba factory.

Signed-off-by: MegaMetapod <48ee6722255b619da9249aa56ff43c3552d60ba3@users.noreply.github.com>

MegaMetapod/pypktools