RATBAG_BUTTON_TYPE_UNKNOWN is not a ratbag_button_action
RATBAG_BUTTON_TYPE_UNKNOWN is not a ratbag_button_action

Just return a NULL. RATBAG_BUTTON_TYPE_UNKNOWN is 0 so no functional
change intendend here.

NoXPhasma/libratbag,whot/libratbag,libratbag/libratbag,whot/libratbag,libratbag/libratbag,cvuchener/libratbag,NoXPhasma/libratbag,libratbag/libratbag,cvuchener/libratbag,whot/libratbag,cvuchener/libratbag,NoXPhasma/libratbag