test: Handle GetVolumePathName errors, prevent access violation (#1626)

test: Handle GetVolumePathName errors, prevent access violation (#1626)

For example GetVolumePathName returns `F:/git_projects` on my computer which
does not fit in a char[4]. As a result GetVolumePathName returns an error and
a std::string is initialized from uninitialized memory which may not contain
a '\0' resulting in out of bounds memory reads.

Co-authored-by: Leander Schulten <Leander.Schulten@tetys.de>