The fixed-width wrappers parsed into a zero-initialized temporary and
copied it back unconditionally, so invalid input overwrote the
destination with zero. Copy back only when the result is not
invalid_argument, as required by [charconv.from.chars]/1.
manually checked modified files for errors, but not committing .clang-format due to the following warning:
>>> Setting `QualifierAlignment` to something other than `Leave`, COULD lead to incorrect code formatting due to incorrect decisions made due to clang-formats lack of complete semantic information. As such extra care should be taken to review code changes made by the use of this option.
