Better #define guard for PIN_EINK_EN

src/ButtonThread.h

@@ -159,7 +159,7 @@ class ButtonThread : public concurrency::OSThread
 
     static void userButtonDoublePressed()
     {
-#if defined(USE_EINK)
+#if defined(USE_EINK) && defined(PIN_EINK_EN)
         digitalWrite(PIN_EINK_EN, digitalRead(PIN_EINK_EN) == LOW);
 #endif
     }

src/Power.cpp

@@ -234,7 +234,7 @@ bool Power::setup()
 void Power::shutdown()
 {
 
-#if defined(USE_EINK)
+#if defined(USE_EINK) && defined(PIN_EINK_EN)
     digitalWrite(PIN_EINK_EN, LOW); //power off backlight first
 #endif