When converting user input the result is zero if the conversion fails. There should be a better error handling, especially in argument/config handling.
cc @laanwj
This is already mentioned in the developer notes: https://github.com/bitcoin/bitcoin/blob/master/doc/developer-notes.md#strings-and-formatting
Please submit a pull request if the current code is not conformant.
Such PR could be a complex refactor. One usage to fix is GetArg(..., uint64_t).
That, imo, should be solved by checking the command line args on init. C.f. #11819