Separate+: Crash in gimp_pixel_rgns_process

GIMP version: 2.10.6

Operating System: Windows 10

Package: Installer from gimp.org

Description of the bug

I recently compiled Separate+ from source (https://osdn.net/projects/separate-plus/). Its menu entry works but the plugin crashes when clicking OK in the menu dialog. GIMP shows LibGimpBase-WARNING: gimp-2.10.exe: gimp_wire_read(): error in the console and the "Plug-in crashed" pop-up shows up. Since the plugin used to work with GIMP 2.8 (I used a precompiled version for 2.8 though), this might be a problem that was introduced somewhere in the development of 2.10.

Reproduction

1. Compile separate+ from source
2. Run GIMP, open any image
3. Click Image>Separate>Separate
4. Confirm dialog with OK
5. Plugin crashes

Is the bug reproducible? Yes, always.

Additional information

#0  0x00007fffb4314cfb in ntdll!RtlIsNonEmptyDirectoryReparsePointAllowed ()
   from C:\WINDOWS\SYSTEM32\ntdll.dll
#1  0x00007fffb431c806 in ntdll!RtlpNtSetValueKey ()
   from C:\WINDOWS\SYSTEM32\ntdll.dll
#2  0x00007fffb431cad1 in ntdll!RtlpNtSetValueKey ()
   from C:\WINDOWS\SYSTEM32\ntdll.dll
#3  0x00007fffb42b9a55 in ntdll!RtlRaiseStatus ()
   from C:\WINDOWS\SYSTEM32\ntdll.dll
#4  0x00007fffb42c7347 in ntdll!memset () from C:\WINDOWS\SYSTEM32\ntdll.dll
#5  0x00007fffb3b298bc in msvcrt!free () from C:\WINDOWS\System32\msvcrt.dll
#6  0x000000006f4df881 in gimp_tile_unref (tile=0x3cd3940,
    dirty=<optimized out>) at gimptile.c:115
#7  0x000000006f4ddeda in gimp_pixel_rgns_process (pri_ptr=0x3c54c40)
    at gimppixelrgn.c:790
#8  0x0000000000409302 in separate_light (drawable=0x28ba300,
    values=0x41f0c8 <values+40>, sc=0x6efb60)
    at ~/gimp_dev/src/separate+/separate-core.c:569
#9  0x000000000040b230 in run (name=0x28e44c0 "plug_in_separate_separate",
    nparams=3, param=0x28c6b80, nreturn_vals=0x6efd44, return_vals=0x6efd48)
    at ~/gimp_dev/src/separate+/separate-gui.c:340
#10 0x000000006f4c2a96 in gimp_proc_run (proc_run=<optimized out>)
    at gimp.c:2439
#11 gimp_loop () at gimp.c:2264
#12 gimp_main (info=<optimized out>, argc=<optimized out>,
    argv=<optimized out>) at gimp.c:671
#13 0x000000000040a86d in main (argc=6, argv=0x10fe940)
    at ~/gimp_dev/src/separate+/separate-gui.c:119

(I replaced the full path to my msys2 home directory with ~ in the trace)