Same bug here. Seems to happen often with firefox, when opening a link, or when
usintg alt+tab to switch to it. So I changed to chromium, which seems to
trigger it at least not that often.

The bug as well recently happend when I switched to eclipse via alt+tab. Here a
log:

schwinn@schwinn-desktop:~$ sudo lspci | grep VGA
06:00.0 VGA compatible controller: NVIDIA Corporation GK208B [GeForce GT 710]
(rev a1)

Oct  7 23:13:23 schwinn-desktop kernel: [ 2726.080132] nouveau 0000:06:00.0:
gr: TRAP ch 4 [003fb96000 Xorg[645]]
Oct  7 23:13:23 schwinn-desktop kernel: [ 2726.080146] nouveau 0000:06:00.0:
gr: GPC0/TPC0/MP trap: global 00000004 [MULTIPLE_WARP_ERRORS] warp 3f000
9 [ILLEGAL_INSTR_ENCODING]
Oct  7 23:13:23 schwinn-desktop kernel: [ 2726.080259] nouveau 0000:06:00.0:
gr: TRAP ch 2 [003fbec000 Xorg[645]]
Oct  7 23:13:23 schwinn-desktop kernel: [ 2726.080268] nouveau 0000:06:00.0:
gr: GPC0/TPC0/MP trap: global 00000004 [MULTIPLE_WARP_ERRORS] warp 7000e
[OOR_ADDR]
Oct  7 23:13:23 schwinn-desktop kernel: [ 2726.080277] nouveau 0000:06:00.0:
gr: TRAP ch 2 [003fbec000 Xorg[645]]
Oct  7 23:13:23 schwinn-desktop kernel: [ 2726.080284] nouveau 0000:06:00.0:
gr: GPC0/TPC0/MP trap: global 00000004 [MULTIPLE_WARP_ERRORS] warp 7000e
[OOR_ADDR]
Oct  7 23:13:23 schwinn-desktop kernel: [ 2726.080292] nouveau 0000:06:00.0:
gr: TRAP ch 2 [003fbec000 Xorg[645]]
Oct  7 23:13:23 schwinn-desktop kernel: [ 2726.080299] nouveau 0000:06:00.0:
gr: GPC0/TPC0/MP trap: global 00000004 [MULTIPLE_WARP_ERRORS] warp 10000e
[OOR_ADDR]
Oct  7 23:13:23 schwinn-desktop kernel: [ 2726.080309] nouveau 0000:06:00.0:
gr: TRAP ch 2 [003fbec000 Xorg[645]]
Oct  7 23:13:23 schwinn-desktop kernel: [ 2726.080316] nouveau 0000:06:00.0:
gr: GPC0/TPC0/MP trap: global 00000004 [MULTIPLE_WARP_ERRORS] warp 26000e
[OOR_ADDR]
Oct  7 23:13:28 schwinn-desktop kernel: [ 2730.413036] nouveau 0000:06:00.0:
fifo: SCHED_ERROR 0a [CTXSW_TIMEOUT]
Oct  7 23:13:28 schwinn-desktop kernel: [ 2730.413057] nouveau 0000:06:00.0:
fifo: runlist 0: scheduled for recovery
Oct  7 23:13:28 schwinn-desktop kernel: [ 2730.413077] nouveau 0000:06:00.0:
fifo: channel 2: killed
Oct  7 23:13:28 schwinn-desktop kernel: [ 2730.413086] nouveau 0000:06:00.0:
fifo: engine 6: scheduled for recovery
Oct  7 23:13:28 schwinn-desktop kernel: [ 2730.413091] nouveau 0000:06:00.0:
fifo: engine 0: scheduled for recovery
Oct  7 23:13:28 schwinn-desktop kernel: [ 2730.413160] nouveau 0000:06:00.0:
Xorg[645]: channel 2 killed!
<reboot>
Oct  7 23:14:37 schwinn-desktop kernel: [    0.000000] Linux version
5.2.0-2-amd64 (debian-kernel@lists.debian.org) (gcc version 8.3.0 (Debian
8.3.0-21)) #1 SMP Debian 5.2.9-2 (2019-08-21)