Update src/specify_cli/__init__.py

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: mbachorik

src/specify_cli/__init__.py

@@ -2868,6 +2868,12 @@ def extension_update(
                         if extension_dir.exists():
                             shutil.rmtree(extension_dir)
                         shutil.copytree(backup_ext_dir, extension_dir)
+                    else:
+                        # If there was no backup directory, the original state may have
+                        # been "no extension directory". In that case, ensure we don't
+                        # leave a newly created (and now failed) extension_dir behind.
+                        if extension_dir.exists():
+                            shutil.rmtree(extension_dir)
 
                     # Remove any NEW command files created by failed install
                     # (files that weren't in the original backup)