Fix #13769 (TokenList: throw internal error when assertion fails)

[danmar]

Example output with assert failure:

$ ./cppcheck 1.c
Checking 1.c ...
cppcheck: lib/tokenlist.cpp:60: TokenList::TokenList(const Settings*): Assertion `1==22' failed.
Aborted (core dumped)

Example output if an internal error is thrown instead:

$ ./cppcheck 1.c > /dev/null
1.c:0:0: error: Bailing out from analysis: Checking file failed: lib/tokenlist.cpp:60: Assertion 1==22 failed [internalError]

[Copilot]

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.