Crash with segmentation violation when target directory exists

When converting a bin file and target directory already exists, this produce a segmentation violation :

 *** Break *** segmentation violation

===========================================================
There was a crash.
This is the entire stack trace of all threads:
===========================================================
#0  0x00007371d96ea3ea in wait4 () from /lib/x86_64-linux-gnu/libc.so.6
#1  0x00007371d9650bdb in ?? () from /lib/x86_64-linux-gnu/libc.so.6
#2  0x00007371db4c394b in TUnixSystem::StackTrace() () from /data/fleg/.conda/envs/grandlib/lib/libCore.so.6.30
#3  0x00007371db4c1296 in TUnixSystem::DispatchSignals(ESignals) () from /data/fleg/.conda/envs/grandlib/lib/libCore.so.6.30
#4  <signal handler called>
#5  0x00005fac8179fbd1 in main ()
===========================================================

This can be bypass using -ow option to remove and recreate the directory.

It would be nice to test the existence of the target dir and warn (and suggest the use of -ow) instead of having a crash.