[issue30249] improve struct.unpack_from's error message like struct.pack_into

[Xiang Zhang]

Change by Xiang Zhang <angwerzx at 126.com>:


----------
resolution:  -> fixed
stage: patch review -> resolved
status: open -> closed

_______________________________________
Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue30249>
_______________________________________