I had a similar problem on Debian 12 64-bit, GNOME 43.9 with X11.
My geany version reported from "LANG=c geany --version" is: geany 1.38 (built on 2022-09-18 with GTK 3.24.34, GLib 2.73.3).
My steps to reproduce:
1. Open geany
2. Press "Control+n" or the icon in the toolbar to create a new file
3. Focus the text input area of the now opened file (the thing where you type in the contents of the file)
4. Crash.
The attachment gdb_backtrace*1 shows the backtrace after the crash in step 4.
My steps to solve this issue:
1. Disable the plugin "project organizer", version 1.38 which is apperently by "Jiri Techet" (according to the tooltip). No need to uninstall the plugin, turning it off sufficed.
I now can no longer reproduce this crash.
Note: I asked about this in debians irc channel #debian. They linked me this and finally asked me to sent this info to you, in case it's helpful.
*1 sha512sum: 651e56ca6fa1f90ee62f3e0cd3c940d8e725e9c6d2c4533f7a0f97c0f217271920a46d777dbb571d679157357641d0231e085ca0888ab191b0f72421be83ea53 gdb_backtrace