Crash with Density/Energy Profile in the Solar System preset

How to reproduce:

1. Create a new session and select the solar system preset
2. Let the simulation run for a few seconds, then stop it.
3. Press Analysis -> Density Profile
4. Observe the crash

Here is a GDB backtrace for all threads. Most notably is probably thread 1 at the very bottom: thread_apply_all_bt.txt

#0  emission_find (instance=0x555556484af0, detail=0, signal_id=11) at ../glib-2.68.4/gobject/gsignal.c:893
        emission = 0x70
        node = <optimized out>
        accumulator = <optimized out>
        emission = {next = 0x555555f88ba0, instance = 0x7ffff66d8f30 <type_rw_lock>, ihint = {signal_id = 4134375216, detail = 32767, run_type = (G_SIGNAL_RUN_FIRST | G_SIGNAL_RUN_CLEANUP | G_SIGNAL_DETAILED | G_SIGNAL_MUST_COLLECT | G_SIGNAL_DEPRECATED | G_SIGNAL_ACCUMULATOR_FIRST_RUN | unknown: 0xf65d0000)}, state = 32767, chain_type = 0x555555f88ba0 [GtkWidget/GtkObject/GInitiallyUnowned]}
        class_closure = <optimized out>
        hlist = <optimized out>
        handler_list = 0x0
        return_accu = <optimized out>
        accu = {g_type = 0x0, data = {{v_int = 0, v_uint = 0, v_long = 0, v_ulong = 0, v_int64 = 0, v_uint64 = 0, v_float = 0, v_double = 0, v_pointer = 0x0}, {v_int = 0, v_uint = 0, v_long = 0, v_ulong = 0, v_int64 = 0, v_uint64 = 0, v_float = 0, v_double = 0, v_pointer = 0x0}}}
        signal_id = 11
        max_sequential_handler_number = <optimized out>
        return_value_altered = 0

Tested in master branch: c1679bd6