Barometer Initialization Crashes Serpent

[nashj]

Running serpent with barometer factors enabled crashes the system on the first LIDAR callback in frontend.cpp.

The following lines cause the crash:

serpent/serpent/src/frontend.cpp

Lines 516 to 521 in a84da0f

	// Save timestamp for barometer interpolation
	if (barometer_enabled) {
	std::lock_guard<std::mutex> guard{barometer_data_mutex};
	barometer_timestamp_buffer.push_back(new_state_time);
	barometer_try_publish();
	}

Likely an issue with how the mutex is being used.