Ocean: Fail trackRecording() when the recording yields no trackable frame

Summary:
`trackRecording()` fell into an unconditional success tail. If `devicePlayer.playNextFrame()` returned an invalid timestamp on the very first iteration, an empty or exhausted recording, the loop broke immediately and the function returned true after moving a still null `anyCamera` and an empty `database` to the caller.

It now returns false when no frame was tracked, leaving the output parameters untouched like every other early exit in the function.

`Database::isEmpty<false>()` is the right predicate and subsumes a separate null camera test: `trackFrame()` adds a pose unconditionally at line 68, so an empty database means no frame was tracked, which in turn means `currentAnyCamera` was never assigned. The sibling reimplementation gates identically at `OnDeviceMapCreatorTracker6DOF.cpp:178`.

No caller exists in fbsource, the only in-repo user of the class reimplements the same loop, so this is reachable through the public API only.

___

Differential Revision: D115260381

fbshipit-source-id: 5e9bb70f6d6f803ad27db300a0c1e48b347969fa

Author: janherlingmeta

impl/ocean/tracking/mapbuilding/PatchTracker.cpp

@@ -300,6 +300,14 @@ bool PatchTracker::trackRecording(Devices::DevicePlayer& devicePlayer, const Str
 #endif
 	}
 
+	if (patchTracker.database_.isEmpty<false>())
+	{
+		Log::error() << "The recording did not provide any trackable frame.";
+		return false;
+	}
+
+	ocean_assert(currentAnyCamera);
+
 	anyCamera = std::move(currentAnyCamera);
 
 	database = std::move(patchTracker.database_);