[Bugfix] Uart bool operator should return enabled state

Author: h2zero

cores/nRF5/Uart.cpp

@@ -246,6 +246,10 @@ size_t Uart::write(const uint8_t data)
   return 1;
 }
 
+Uart::operator bool() {
+  return nrfUart->ENABLE == UART_ENABLE_ENABLE_Enabled;
+}
+
 #if defined(NRF52_SERIES)
   #define NRF_UART0_IRQn UARTE0_UART0_IRQn
 #elif defined(NRF51_SERIES)

cores/nRF5/Uart.h

@@ -47,10 +47,10 @@ class Uart : public HardwareSerial
 
     void IrqHandler();
 
-    operator bool() { return true; }
+    operator bool();
 
   private:
-    NRF_UART_Type *nrfUart;
+    NRF_UART_Type *nrfUart{nullptr};
     RingBuffer rxBuffer;
 
     IRQn_Type IRQn;