Non-void functions don't return value

[nseidle]

It compiles but with warnings. I think they can be solved pretty easily.

Compiled on Artemis (tighter compiler warnings):

C:\Users\nathan.seidle\Dropbox\Apps\Arduino\libraries\SparkFun_Qwiic_Button_Arduino_Library-master\src\SparkFun_Qwiic_Button.cpp: In member function 'uint8_t QwiicButton::readSingleRegister(Qwiic_Button_Register)':
C:\Users\nathan.seidle\Dropbox\Apps\Arduino\libraries\SparkFun_Qwiic_Button_Arduino_Library-master\src\SparkFun_Qwiic_Button.cpp:301:1: warning: control reaches end of non-void function [-Wreturn-type]
}
^
C:\Users\nathan.seidle\Dropbox\Apps\Arduino\libraries\SparkFun_Qwiic_Button_Arduino_Library-master\src\SparkFun_Qwiic_Button.cpp: In member function 'uint16_t QwiicButton::readDoubleRegister(Qwiic_Button_Register)':
C:\Users\nathan.seidle\Dropbox\Apps\Arduino\libraries\SparkFun_Qwiic_Button_Arduino_Library-master\src\SparkFun_Qwiic_Button.cpp:317:1: warning: control reaches end of non-void function [-Wreturn-type]
}