Raise STM32F1 UART IRQ Priority, add error handling (#19301)

(Error handling for Overrun, Framing and Parity.)

Marlin/src/HAL/STM32/MarlinSerial.cpp

@@ -55,10 +55,8 @@
 
 void MarlinSerial::begin(unsigned long baud, uint8_t config) {
   HardwareSerial::begin(baud, config);
-  // replace the IRQ callback with the one we have defined
-  #if ENABLED(EMERGENCY_PARSER)
-    _serial.rx_callback = _rx_callback;
-  #endif
+  // Replace the IRQ callback with the one we have defined
+  TERN_(EMERGENCY_PARSER, _serial.rx_callback = _rx_callback);
 }
 
 // This function is Copyright (c) 2006 Nicholas Zambetti.