[rdoupe]

Fixes #1254

What and why

GetCurrentProgramScene no longer aborts OBS when there is no program scene. It answers with null names and UUIDs instead, as GetSceneList already does (upstream obsproject/obs-websocket#1349, reported by stevets).

• In Studio Mode the frontend keeps the program scene as a weak reference (OBSBasic::programScene). obs_frontend_get_current_scene() returns obs_weak_source_get_source() of it (frontend/OBSStudioAPI.cpp.hpp line 54), which is NULL once that scene is removed and destroyed. GetCurrentProgramScene() (plugins/obs-websocket/src/requesthandler/RequestHandler_Scenes.cpp) put obs_source_get_name(NULL) into a json string. That throws std::logic_error ("basic_string: construction from null is not valid") on the websocket thread, and OBS aborts (SIGSEGV in strlen on macOS). One client sending RemoveScene for the program scene and then GetCurrentProgramScene takes OBS down, in the middle of a stream or a recording.
• The fork fix, requesthandler: Report a missing program or preview scene as null obs-websocket#17, ports andrewsoncha's check from requesthandler: Fix GtCurrentProgramScene crash obsproject/obs-websocket#1353 (open upstream; co-author on both commits): sceneName, sceneUuid, currentProgramSceneName and currentProgramSceneUuid are null when there is no program scene. GetCurrentPreviewScene has the same unchecked shape and gets the same check. This PR moves the submodule to it.
• Nothing changes while the scene exists, and the status stays Success. GetSceneList has reported the same state as currentProgramSceneName: null all along, so clients already see null there.
• This is the other half of the null path in bug: obs-websocket: RemoveScene removes the last scene and the next GetCurrentProgramScene aborts OBS (upstream obsproject/obs-studio#10532, #10533) #519. bug: obs-websocket: RemoveScene removes the last scene and the next GetCurrentProgramScene aborts OBS (upstream obsproject/obs-studio#10532, #10533) #519 fixed the scene count, so RemoveScene can't remove the last scene any more. In Studio Mode the program scene can still be removed while other scenes remain.

Reproduced in release v0.1.0-beta.20261014 (AppImage) and on master bbf55a0. Headless: private Xvfb, fresh HOME, dbus-run-session, --multi. One websocket client sends SetStudioModeEnabled true, CreateScene "victim", SetCurrentProgramScene "victim", RemoveScene "victim", waits 1 s, then sends GetSceneList, GetCurrentProgramScene, and SetCurrentProgramScene "Scene" + GetCurrentProgramScene.

	v0.1.0-beta.20261014	master bbf55a0	This branch, C libobs lane	This branch, Rust libobs lane
GetSceneList program after the removal	null	null	null	null
GetCurrentProgramScene	SIGABRT: terminate called after throwing an instance of 'std::logic_error' / basic_string: construction from null is not valid	SIGABRT, same message	Success, all four fields null	Success, all four fields null
Then SetCurrentProgramScene "Scene" + GetCurrentProgramScene	(OBS gone)	(OBS gone)	"Scene"	"Scene"

Removing the preview scene instead is fine everywhere: the frontend moves the preview to another scene.

RED → GREEN

• RED commit: 031a72c test/cmocka: Add failing test for GetCurrentProgramScene without a program scene. test_ws_current_scene_removed builds the plugin's scene requests (RequestHandler_Scenes.cpp with Request.cpp and the Utils helpers it calls) against libobs, the way test_ws_transform_bounds does. The frontend calls answer from weak references to a real scene, as OBSStudioAPI does in Studio Mode. The guards program_scene_reported and preview_scene_reported pass. removed_program_scene_reported_null and removed_preview_scene_reported_null fail with GetCurrentProgramScene threw 'basic_string: construction from null is not valid' (the same for the preview). That is 2 of 4 failing, with ENABLE_RUST_LIBOBS OFF and ON. Linux only, like the other websocket request tests. The cases skip without a display (checked with DISPLAY unset).
• GREEN: 0128dd5 moves plugins/obs-websocket from d79d2c2 to 0d663ee, the merged fork fix (requesthandler: Report a missing program or preview scene as null obs-websocket#17; same tree as the commit tested here). 4 of 4 pass in both lanes. Full OBS build (frontend + obs-websocket) in both lanes. Full ctest -j4 (private Xvfb, dbus-run-session, fresh HOME, system libobs-opengl masked, TMPDIR unset): 282/282 in both lanes. Every PipeWire/PulseAudio test ran. Skipped only open_crashes_without_obs_core (both lanes) and, in the Rust lane, test_startup_shutdown_cycles: its one case skips when one of its 2000 obs_startup() calls fails under load, and it passed on a rerun alone. clang-format 22.1 and gersemi 0.25.0 clean.
• Real app: the table above (the release, master, and this branch built in both lanes, run with the same websocket script).

Checklist

• Base is master
• I claimed the issue, or no one else has an open PR for it
• Characterization test (if the unit had none), then RED, then GREEN commits
• (Optional) Local gate passed and the pushed head is stamped; otherwise PR CI runs the full suite
• Warning or flag changes (-W..., ratchets): none
• Intentional differences from C listed in the parity test header and rust/README.md (ports): not a port

AI note: Claude Code (Claude Opus 5.5) wrote the code, the test, the commit messages and this text under the submitter's direction, and ran the tests above on the submitter's machines.

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