I resolved the crash problem in a hacky way.
Within the library, edit the file Speaker.cpp
Edit line 12 to read :
ledcSetup(TONE_PIN_CHANNEL, 1000, 13);
I changed the 0 in the second parameter to a 1000.
This is a frequency setting. I don't know what it does.
It prevents the crash, allows a beep to be played, but the beep duration is wrong.