More detailed serial config error

Marlin/src/HAL/AVR/HAL.h

   #define MYSERIAL1 TERN(BLUETOOTH, btSerial, MSerial0)
 #else
   #if !WITHIN(SERIAL_PORT, -1, 3)
-    #error "SERIAL_PORT must be from -1 to 3. Please update your configuration."
+    #error "SERIAL_PORT must be from 0 to 3. You can also use -1 if the board supports Native USB."
   #endif
   #define MYSERIAL1 customizedSerial1
 
   #ifdef SERIAL_PORT_2
     #if !WITHIN(SERIAL_PORT_2, -1, 3)
-      #error "SERIAL_PORT_2 must be from -1 to 3. Please update your configuration."
+      #error "SERIAL_PORT_2 must be from 0 to 3. You can also use -1 if the board supports Native USB."
     #endif
     #define MYSERIAL2 customizedSerial2
   #endif
 
 #ifdef MMU2_SERIAL_PORT
   #if !WITHIN(MMU2_SERIAL_PORT, -1, 3)
-    #error "MMU2_SERIAL_PORT must be from -1 to 3. Please update your configuration."
+    #error "MMU2_SERIAL_PORT must be from 0 to 3. You can also use -1 if the board supports Native USB."
   #endif
   #define MMU2_SERIAL mmuSerial
 #endif
 
 #ifdef LCD_SERIAL_PORT
   #if !WITHIN(LCD_SERIAL_PORT, -1, 3)
-    #error "LCD_SERIAL_PORT must be from -1 to 3. Please update your configuration."
+    #error "LCD_SERIAL_PORT must be from 0 to 3. You can also use -1 if the board supports Native USB."
   #endif
   #define LCD_SERIAL lcdSerial
   #if HAS_DGUS_LCD

Marlin/src/HAL/DUE/HAL.h

 #elif WITHIN(SERIAL_PORT, 0, 3)
   #define MYSERIAL1 MSERIAL(SERIAL_PORT)
 #else
-  #error "The required SERIAL_PORT must be from -1 to 3. Please update your configuration."
+  #error "The required SERIAL_PORT must be from 0 to 3. You can also use -1 if the board supports Native USB."
 #endif
 
 #ifdef SERIAL_PORT_2
   #elif WITHIN(SERIAL_PORT_2, 0, 3)
     #define MYSERIAL2 MSERIAL(SERIAL_PORT_2)
   #else
-    #error "SERIAL_PORT_2 must be from -1 to 3. Please update your configuration."
+    #error "SERIAL_PORT_2 must be from 0 to 3. You can also use -1 if the board supports Native USB."
   #endif
 #endif
 
   #if WITHIN(MMU2_SERIAL_PORT, 0, 3)
     #define MMU2_SERIAL MSERIAL(MMU2_SERIAL_PORT)
   #else
-    #error "MMU2_SERIAL_PORT must be from 0 to 3. Please update your configuration."
+    #error "MMU2_SERIAL_PORT must be from 0 to 3."
   #endif
 #endif
 
   #elif WITHIN(LCD_SERIAL_PORT, 0, 3)
     #define LCD_SERIAL MSERIAL(LCD_SERIAL_PORT)
   #else
-    #error "LCD_SERIAL_PORT must be from -1 to 3. Please update your configuration."
+    #error "LCD_SERIAL_PORT must be from 0 to 3. You can also use -1 if the board supports Native USB."
   #endif
 #endif
 

Marlin/src/HAL/LPC1768/HAL.h

 #elif WITHIN(SERIAL_PORT, 0, 3)
   #define MYSERIAL1 MSERIAL(SERIAL_PORT)
 #else
-  #error "SERIAL_PORT must be from -1 to 3. Please update your configuration."
+  #error "SERIAL_PORT must be from 0 to 3. You can also use -1 if the board supports Native USB."
 #endif
 
 #ifdef SERIAL_PORT_2
   #elif WITHIN(SERIAL_PORT_2, 0, 3)
     #define MYSERIAL2 MSERIAL(SERIAL_PORT_2)
   #else
-    #error "SERIAL_PORT_2 must be from -1 to 3. Please update your configuration."
+    #error "SERIAL_PORT_2 must be from 0 to 3. You can also use -1 if the board supports Native USB."
   #endif
 #endif
 
   #elif WITHIN(MMU2_SERIAL_PORT, 0, 3)
     #define MMU2_SERIAL MSERIAL(MMU2_SERIAL_PORT)
   #else
-    #error "MMU2_SERIAL_PORT must be from -1 to 3. Please update your configuration."
+    #error "MMU2_SERIAL_PORT must be from 0 to 3. You can also use -1 if the board supports Native USB."
   #endif
 #endif
 
   #elif WITHIN(LCD_SERIAL_PORT, 0, 3)
     #define LCD_SERIAL MSERIAL(LCD_SERIAL_PORT)
   #else
-    #error "LCD_SERIAL_PORT must be from -1 to 3. Please update your configuration."
+    #error "LCD_SERIAL_PORT must be from 0 to 3. You can also use -1 if the board supports Native USB."
   #endif
   #if HAS_DGUS_LCD
     #define SERIAL_GET_TX_BUFFER_FREE() MSerial0.available()

Marlin/src/HAL/SAMD51/HAL.h

   #elif WITHIN(SERIAL_PORT, 0, 3)
     #define MYSERIAL1 MSERIAL(SERIAL_PORT)
   #else
-    #error "SERIAL_PORT must be from -1 to 3. Please update your configuration."
+    #error "SERIAL_PORT must be from 0 to 3. You can also use -1 if the board supports Native USB."
   #endif
 
   #ifdef SERIAL_PORT_2
     #elif WITHIN(SERIAL_PORT_2, 0, 3)
       #define MYSERIAL2 MSERIAL(SERIAL_PORT_2)
     #else
-      #error "SERIAL_PORT_2 must be from -1 to 3. Please update your configuration."
+      #error "SERIAL_PORT_2 must be from 0 to 3. You can also use -1 if the board supports Native USB."
     #endif
   #endif
 
     #elif WITHIN(MMU2_SERIAL_PORT, 0, 3)
       #define MMU2_SERIAL MSERIAL(MMU2_SERIAL_PORT)
     #else
-      #error "MMU2_SERIAL_PORT must be from -1 to 3. Please update your configuration."
+      #error "MMU2_SERIAL_PORT must be from 0 to 3. You can also use -1 if the board supports Native USB."
     #endif
   #endif
 
     #elif WITHIN(LCD_SERIAL_PORT, 0, 3)
       #define LCD_SERIAL MSERIAL(LCD_SERIAL_PORT)
     #else
-      #error "LCD_SERIAL_PORT must be from -1 to 3. Please update your configuration."
+      #error "LCD_SERIAL_PORT must be from 0 to 3. You can also use -1 if the board supports Native USB."
     #endif
   #endif
 

Marlin/src/HAL/STM32/HAL.h

 #elif WITHIN(SERIAL_PORT, 1, 6)
   #define MYSERIAL1 MSERIAL(SERIAL_PORT)
 #else
-  #error "SERIAL_PORT must be -1 or from 1 to 6. Please update your configuration."
+  #error "SERIAL_PORT must be from 1 to 6. You can also use -1 if the board supports Native USB."
 #endif
 
 #ifdef SERIAL_PORT_2
   #elif WITHIN(SERIAL_PORT_2, 1, 6)
     #define MYSERIAL2 MSERIAL(SERIAL_PORT_2)
   #else
-    #error "SERIAL_PORT_2 must be -1 or from 1 to 6. Please update your configuration."
+    #error "SERIAL_PORT_2 must be from 1 to 6. You can also use -1 if the board supports Native USB."
   #endif
 #endif
 
   #elif WITHIN(MMU2_SERIAL_PORT, 1, 6)
     #define MMU2_SERIAL MSERIAL(MMU2_SERIAL_PORT)
   #else
-    #error "MMU2_SERIAL_PORT must be -1 or from 1 to 6. Please update your configuration."
+    #error "MMU2_SERIAL_PORT must be from 1 to 6. You can also use -1 if the board supports Native USB."
   #endif
 #endif
 
   #elif WITHIN(LCD_SERIAL_PORT, 1, 6)
     #define LCD_SERIAL MSERIAL(LCD_SERIAL_PORT)
   #else
-    #error "LCD_SERIAL_PORT must be -1 or from 1 to 6. Please update your configuration."
+    #error "LCD_SERIAL_PORT must be from 1 to 6. You can also use -1 if the board supports Native USB."
   #endif
   #if HAS_DGUS_LCD
     #define SERIAL_GET_TX_BUFFER_FREE() LCD_SERIAL.availableForWrite()

Marlin/src/HAL/STM32F1/HAL.h

 #else
   #define MYSERIAL1 MSERIAL(1) // dummy port
   #if NUM_UARTS == 5
-    #error "SERIAL_PORT must be -1 or from 1 to 5. Please update your configuration."
+    #error "SERIAL_PORT must be from 1 to 5. You can also use -1 if the board supports Native USB."
   #else
-    #error "SERIAL_PORT must be -1 or from 1 to 3. Please update your configuration."
+    #error "SERIAL_PORT must be from 1 to 3. You can also use -1 if the board supports Native USB."
   #endif
 #endif
 
   #else
     #define MYSERIAL2 MSERIAL(1) // dummy port
     #if NUM_UARTS == 5
-      #error "SERIAL_PORT_2 must be -1 or from 1 to 5. Please update your configuration."
+      #error "SERIAL_PORT_2 must be from 1 to 5. You can also use -1 if the board supports Native USB."
     #else
-      #error "SERIAL_PORT_2 must be -1 or from 1 to 3. Please update your configuration."
+      #error "SERIAL_PORT_2 must be from 1 to 3. You can also use -1 if the board supports Native USB."
     #endif
   #endif
 #endif
   #else
     #define MMU2_SERIAL MSERIAL(1) // dummy port
     #if NUM_UARTS == 5
-      #error "MMU2_SERIAL_PORT must be -1 or from 1 to 5. Please update your configuration."
+      #error "MMU2_SERIAL_PORT must be from 1 to 5. You can also use -1 if the board supports Native USB."
     #else
-      #error "MMU2_SERIAL_PORT must be -1 or from 1 to 3. Please update your configuration."
+      #error "MMU2_SERIAL_PORT must be from 1 to 3. You can also use -1 if the board supports Native USB."
     #endif
   #endif
 #endif
   #else
     #define LCD_SERIAL MSERIAL(1) // dummy port
     #if NUM_UARTS == 5
-      #error "LCD_SERIAL_PORT must be -1 or from 1 to 5. Please update your configuration."
+      #error "LCD_SERIAL_PORT must be from 1 to 5. You can also use -1 if the board supports Native USB."
     #else
-      #error "LCD_SERIAL_PORT must be -1 or from 1 to 3. Please update your configuration."
+      #error "LCD_SERIAL_PORT must be from 1 to 3. You can also use -1 if the board supports Native USB."
     #endif
   #endif
   #if HAS_DGUS_LCD

Marlin/src/HAL/TEENSY31_32/HAL.cpp

 #define IMPLEMENT_SERIAL(X)  _IMPLEMENT_SERIAL(X)
 #if WITHIN(SERIAL_PORT, 0, 3)
   IMPLEMENT_SERIAL(SERIAL_PORT);
+#else
+  #error "SERIAL_PORT must be from 0 to 3."
 #endif
 USBSerialType USBSerial(false, SerialUSB);
 

Marlin/src/HAL/TEENSY35_36/HAL.h

 #elif WITHIN(SERIAL_PORT, 0, 3)
   #define MYSERIAL1 MSERIAL(SERIAL_PORT)
   DECLARE_SERIAL(SERIAL_PORT);
+#else
+  #error "SERIAL_PORT must be from 0 to 3, or -1 for Native USB."
 #endif
 
 #define HAL_SERVO_LIB libServo

Marlin/src/HAL/TEENSY40_41/HAL.h

   DECLARE_SERIAL(SERIAL_PORT);
   #define MYSERIAL1 MSERIAL(SERIAL_PORT)
 #else
-  #error "The required SERIAL_PORT must be from -1 to 8. Please update your configuration."
+  #error "The required SERIAL_PORT must be from 0 to 8, or -1 for Native USB."
 #endif
 
 #ifdef SERIAL_PORT_2
   #elif WITHIN(SERIAL_PORT_2, 0, 8)
     #define MYSERIAL2 MSERIAL(SERIAL_PORT_2)
   #else
-    #error "SERIAL_PORT_2 must be from -2 to 8. Please update your configuration."
+    #error "SERIAL_PORT_2 must be from 0 to 8, or -1 for Native USB, or -2 for Ethernet."
   #endif
 #endif