Crash in add_source() (GcalSourceDialog)
This crash is very very similar to #416 (closed). Again the signals connected in gcal_source_dialog_set_property() are not being properly disconnected:
Truncated backtrace:
Thread no. 1 (10 frames)
#0 GCAL_IS_MANAGER at ../src/gcal-manager.h:32
#1 gcal_manager_get_source at ../src/gcal-manager.c:1001
#2 add_source at ../src/gcal-source-dialog.c:329
#3 ffi_call_unix64 at ../src/x86/unix64.S:76
#4 ffi_call at ../src/x86/ffi64.c:525
#5 g_cclosure_marshal_generic at gclosure.c:1496
#10 on_client_connected at ../src/gcal-manager.h:32
#11 g_simple_async_result_complete at gsimpleasyncresult.c:802
#12 cal_client_connect_wait_for_connected_cb at /usr/src/debug/evolution-data-server-3.30.5-1.fc29.x86_64/src/calendar/libecal/e-cal-client.c:1736
#13 g_task_return_now at gtask.c:1148
Full backtrace downstream. This time my guess is the GcalSourceDialog is dead, but its old manager is not. Notice it crashes on line 329, which in 3.32 is using self->manager rather than the manager parameter of the signal handler. self=0x450 in the full backtrace and that's a pretty clear sign the GcalSourceDialog was already destroyed and should have cleaned up its signal handler.
This time there's no evidence of a second manager object involved, so just switching to g_signal_connect_object() should fix it, but since the parameter is writable after construction it ought to handle multiple writes anyway.