Hello.

And yes, I know it's weird, but this happends consistently on two different Gentoo installations.

The recipe is as follows:
- copyq (a clipboard manager) is running
- I use the magic want tool to select irregular shapes, and press control-x to cut
- wait a couple seconds, gimp will close and output this:
- I tested 2.8.14 and 2.9.4 with copyq 2.5 and 2.7, all combos produce the same results in two different installations
- if I repeat the same steps without copyq, all works fine, using another clipboard manager (such as parcellite) works fine as well

=====
$ gimp
La dirección proporcionada está vacía
[added translation: provided path/adress is empty]
This is a development version of GIMP.  Debug messages may appear here.


(gimp:10722): Gtk-WARNING **: Theme directory base/ of theme oxygen has no size field


(gimp:10722): Gimp-Widgets-CRITICAL **: gimp_device_info_set_device: assertion '(info->device == NULL && GDK_IS_DEVICE (device)) || (GDK_IS_DEVICE (info->device) && device == NULL)' failed
gimp_display_shell_profile_update
gimp_display_shell_profile_update
Error creating proxy: La dirección proporcionada está vacía (g-io-error-quark, 13)
magic match 4 on file-jpeg-load
best magic match on file-jpeg-load
jpeg-load: found Exif block (2857 bytes)
jpeg-load: found image comment (118 bytes)

** (file-jpeg:12891): WARNING **: Directory OlympusCs, entry 0x0101: Strip 0 is outside of the data area; ignored.

gimp_display_shell_profile_update
src_profile: GIMP built-in sRGB
src_format:  R'G'B'A u8
dest_format: R'G'B'A u8
gimp_display_shell_profile_update
src_profile: GIMP built-in sRGB
src_format:  R'G'B'A u8
dest_format: R'G'B'A u8
gimp_pickable_contiguous_region_by_seed: foo took 2,9667 seconds
The program 'gimp' received an X Window System error.
This probably reflects a bug in the program.
The error was 'BadWindow (invalid Window parameter)'.
  (Details: serial 105100 error_code 3 request_code 18 minor_code 0)
  (Note to programmers: normally, X errors are reported asynchronously;
   that is, you will receive the error a while after causing it.
   To debug your program, run it with the --sync command line
   option to change this behavior. You can then get a meaningful
   backtrace from your debugger if you break on the gdk_x_error() function.)