Arduino Nano Every Compiling Missing " HardwareSerial.h"

Ive spent nearly 2 days just staring at the screen when the following error occurs, I have fully wiped my Arduino IDE from the computer and reinstalled but the same error continues with a missing library:

Arduino: 1.8.12 (Windows 10), Board: “Arduino Nano Every, ATMEGA328”

C:\Users*******\Documents\Arduino\libraries\RadioHead\RH_Serial.cpp:13:11: fatal error: HardwareSerial.h: No such file or directory

#include <HardwareSerial.h>


compilation terminated.

exit status 1
Error compiling for board Arduino Nano Every.

This report would have more information with
“Show verbose output during compilation”
option enabled in File → Preferences.

Moved your topic to it's current location as it is more suitable.

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The Nano Every is not based on the 328P chip, so Board: "Arduino Nano Every, ATMEGA328" does not make sense to me.

And the RH library is, to my knowledge, written for AVR boards (so not for the Nano Every).