bare `swaybg` spawned on every config load with zero backgrounds configured

Sway Version:

• sway version 1.12 (arch package 1:1.12-4).

Debug Log:

• No sway -d capture; the behavior is fully described by the code path plus the journal lines below. The spawned process only ever logs:
  • Could not find config for output HDMI-A-1 (...)
  • Could not find config for output eDP-1 (...)
  • recurring at session start, every reload, each hotplug and each VT switch.

Configuration File:

• No output ... bg directive anywhere in the config (wallpaper is handled by an external layer shell client), confirmed via swaymsg -t get_config. Default configuration otherwise.

Stack Trace:

• N/A, no crash.

Description:

• Every config load and reload spawns a bare swaybg with no output arguments (load_main_config calls spawn_swaybg unconditionally; with no backgrounds the command vector is just ["swaybg"]). The process does nothing except log the lines above for each output on every output change. Observed fresh swaybg PIDs at session start and after reloads.
• Proposal: skip the spawn when no output config carries a background (the length == 2 case in spawn_swaybg), or guard at the load_main_config call site. A PR is attached (#9282).