Timeshift crashes if disk is full

[ygerlach]

Describe the bug
If the drive is full, time shift can not be started, as it crashes instantly. This is bad, as it robs unexperienced users from the ability to delete snapshots to restore some disk space.

To Reproduce
Steps to reproduce the behavior:

1. Check timeshift works as intended (disable automatic snapshot creation during the test)
2. Create a file using the rest of the disk. I used dd if=/dev/urandom of=big.file bs=1M status=progress and waited for it to fail with "No space left"
3. Confirm a full disk with df -h
4. try to start timeshift with a full disk

Expected behavior
Timeshift should start but maybe display a warning, that snapshot creation is disabled, because the drive is too full. Deletion of snapshots should always be possible.

Stack Trace

Program received signal SIGSEGV, Segmentation fault.
__strlen_avx2 () at ../sysdeps/x86_64/multiarch/strlen-avx2.S:65
65 ../sysdeps/x86_64/multiarch/strlen-avx2.S: No such file or directory.
(gdb) bt
#0  __strlen_avx2 () at ../sysdeps/x86_64/multiarch/strlen-avx2.S:65
#1  0x00007ffff7ee9703 in  () at /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007ffff7ee9f3f in  () at /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007ffff7eea35d in g_spawn_sync () at /lib/x86_64-linux-gnu/libglib-2.0.so.0
#4  0x00005555555ef758 in tee_jee_process_helper_exec_script_sync
    (script=0x55555565470c "echo 'ok'", std_out=0x7fffffffe280, std_err=0x7fffffffe288, supress_errors=1, run_as_admin=0, cleanup_tmp=1, print_to_terminal=0)
    at ../src/Utility/TeeJee.Process.vala:126
#5  0x00005555555eec98 in tee_jee_process_helper_init_tmp (subdir_name=0x555555648080 "timeshift") at ../src/Utility/TeeJee.Process.vala:44
#6  0x0000555555563b58 in app_gtk_main (args=0x7fffffffe4e8, args_length1=2) at ../src/AppGtk.vala:73
#7  0x0000555555563c21 in main (argc=2, argv=0x7fffffffe4e8) at ../src/AppGtk.vala:51

Timeshift crashes before the first print to stdout or stderr happens. Even with --debug

System:

• Linux Distribution Name and Version: Linux Mint 20.3 / Ubuntu 20.04
• Desktop: Gnome
• Application Version: 24.06.3
• Mode: btrfs (but it crashes so early, it probably does not matter)