Use g_printerr() instead.
g_error() calls abort after outputting the message
so these blocks' return statements and free()s
were unreachable.
Aditionally, fix wrong void returns on non-void
function, drop trailing whitespace before newline and
add \n's as needed (default handler won't add one).
xml_files_path and hex_files_path variable are not initialized.
There are chances that corruption happens when uninitialized
variables are freed, so init them to NULL before use.
https://bugzilla.gnome.org/show_bug.cgi?id=748351
