Check if #POWER defined, thanks to @QDaniel !

src/Power.cpp

@@ -6,24 +6,30 @@
 #include "Port.h"
 
 void Power_Init(void) {
+#ifdef POWER
 #if (POWER >= 0 && POWER <= MAX_GPIO)
 	pinMode(POWER, OUTPUT); // Only necessary for GPIO. For port-expander it's done (previously) via Port_init()
 #endif
+#endif
 }
 
 // Switch on peripherals. Please note: meaning of POWER_ON is HIGH per default. But is LOW in case of INVERT_POWER is enabled.
 void Power_PeripheralOn(void) {
+#ifdef POWER
 	Port_Write(POWER, POWER_ON, false);
 #ifdef BUTTONS_LED
 	Port_Write(BUTTONS_LED, HIGH, false);
 #endif
 	delay(50); // Give peripherals some time to settle down
+#endif
 }
 
 // Switch off peripherals. Please note: meaning of POWER_OFF is LOW per default. But is HIGH in case of INVERT_POWER is enabled.
 void Power_PeripheralOff(void) {
+#ifdef POWER
 	Port_Write(POWER, POWER_OFF, false);
 #ifdef BUTTONS_LED
 	Port_Write(BUTTONS_LED, LOW, false);
 #endif
+#endif
 }