The crash is reproduceable. You can delete the tag, but renaming it always causes a crash. If you're interested in the save file, what would be a good way to send it to you? Note that it's fairly large, bit over 100MB, and using a bunch of mods.

The mod Quick Map Tag Teleport (0.2.72) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event QuickMapTagTeleport::on_chart_tag_modified (ID 161)
QuickMapTagTeleport/scripts/gui/qmtt.lua:111: bad argument #1 of 2 to 'pairs' (table expected, got nil)
stack traceback:
[C]: in function 'pairs'
QuickMapTagTeleport/scripts/gui/qmtt.lua:111: in function 'handle_chart_tag_modified'
QuickMapTagTeleport/control.lua:180: in function <QuickMapTagTeleport/control.lua:179>

are you on Nauvis?

Yes, the character is on Nauvis

I would like to clarify something...
You say "You can delete the tag, but renaming it always causes a crash"
Do you mean that deleting a tag is working and that trying to change the tag's text is causing a crash?

Also - I am about to release an entirely new/rewritten Mod in the next few days called TeleportFavorites. I hate to leave you in the lurch on this issue (and I won't), but this should not be an issue in the new release.

Exactly. Deleting the tag works, trying to change the text causes the crash.

No worries, looking forward to the new version. A workaround is available anyway with deleting the tag in question.

Great! I'll get back to you soon

New version:

https://mods.factorio.com/mod/TeleportFavorites