Cannot Compile Transmitter Example on 8266

[clmail999-sketch]

Hi,
Do you know why the transmitter example won't compile on an ESP8266 board? I get the error below with both NodeMCU 1.0 and Generic ESP8266 Module selected in the Arduino IDE (version 2.3.6). (No changes to the example code.)
Thanks,
Chris

In file included from c:\Users\clmai\OneDrive\Documents\Arduino\libraries\WirelessOregonV2-master\WlessOregonV2.cpp:1:
c:\Users\clmai\OneDrive\Documents\Arduino\libraries\WirelessOregonV2-master\WlessOregonV2.cpp: In member function 'void OregonSensor::sendOne()':
C:\Users\clmai\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\3.1.2\cores\esp8266/Arduino.h:205:60: error: cannot convert 'volatile uint32_t*' {aka 'volatile unsigned int*'} to 'volatile uint8_t*' {aka 'volatile unsigned char*'} in initialization
205 | #define portOutputRegister(port) (((port)==_PORT_GPIO16)?((volatile uint32_t*) &GP16O):((volatile uint32_t*) &GPO))
| ~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| |
| volatile uint32_t* {aka volatile unsigned int*}
c:\Users\clmai\OneDrive\Documents\Arduino\libraries\WirelessOregonV2-master\WlessOregonV2.cpp:21:32: note: in expansion of macro 'portOutputRegister'
21 | volatile uint8_t tx_out = portOutputRegister(tx_port);
| ^~~~~~~~~~~~~~~~~~
c:\Users\clmai\OneDrive\Documents\Arduino\libraries\WirelessOregonV2-master\WlessOregonV2.cpp: In member function 'void OregonSensor::sendZero()':
C:\Users\clmai\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\3.1.2\cores\esp8266/Arduino.h:205:60: error: cannot convert 'volatile uint32_t' {aka 'volatile unsigned int*'} to 'volatile uint8_t*' {aka 'volatile unsigned char*'} in initialization
205 | #define portOutputRegister(port) (((port)==_PORT_GPIO16)?((volatile uint32_t*) &GP16O):((volatile uint32_t*) &GPO))
| ~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| |
| volatile uint32_t* {aka volatile unsigned int*}
c:\Users\clmai\OneDrive\Documents\Arduino\libraries\WirelessOregonV2-master\WlessOregonV2.cpp:31:32: note: in expansion of macro 'portOutputRegister'
31 | volatile uint8_t *tx_out = portOutputRegister(tx_port);
| ^~~~~~~~~~~~~~~~~~
exit status 1

Compilation error: exit status 1