The destructor unconditionally unref'd current_modem, manager and
connection, but the constructor can leave them NULL or already-unref'd:
- On the mm_manager_new_sync failure path the ctor unref'd connection
without nulling it, so the dtor unref'd it a second time -> double-free.
- On the g_bus_get_sync failure path all three stay NULL, and in the
common no-WWAN-hardware case current_modem is NULL, so the dtor ran
g_object_unref(NULL) -> G_IS_OBJECT assertion criticals.
Use g_clear_object() in the failing ctor path (unref + null) and in the
destructor (NULL-safe unref + null). Teardown is now safe for every ctor
outcome (bus fail, MM fail, no modem, normal), and a normal run still
unrefs each owned ref exactly once.
Alex
4764a62afc