core: add assertion in two inline functions

src/core/manager.h

@@ -420,6 +420,7 @@ struct Manager {
 };
 
 static inline usec_t manager_default_timeout_abort_usec(Manager *m) {
+        assert(m);
         return m->default_timeout_abort_set ? m->default_timeout_abort_usec : m->default_timeout_stop_usec;
 }
 

src/core/service.h

@@ -192,6 +192,7 @@ struct Service {
 };
 
 static inline usec_t service_timeout_abort_usec(Service *s) {
+        assert(s);
         return s->timeout_abort_set ? s->timeout_abort_usec : s->timeout_stop_usec;
 }