Fix UBSAN bugs #871

Job	Run time
build (macos-latest, esp8266, gcc)	27m 18s
build (macos-latest, host, gcc)	18m 59s
build (macos-latest, rp2040, gcc)	13m 27s
build (ubuntu-latest, esp8266, gcc)	18m 9s
build (ubuntu-latest, host, clang, Host)	23m 33s
build (ubuntu-latest, host, gcc)	21m 19s
build (ubuntu-latest, host, gcc64, Host)	20m 31s
build (ubuntu-latest, rp2040, gcc)	17m 25s
build (windows-latest, esp8266, gcc)	9m 24s
build (windows-latest, host, gcc)	27m 58s
build (windows-latest, rp2040, gcc)	8m 42s
	3h 26m 45s

Provide feedback