tree-wide: check parameter before dereferencing

src/socket-proxy/socket-proxyd.c

@@ -95,9 +95,13 @@ static int idle_time_cb(sd_event_source *s, uint64_t usec, void *userdata) {
 }
 
 static int connection_release(Connection *c) {
-        Context *context = c->context;
+        Context *context;
         int r;
 
+        assert(c);
+
+        context = ASSERT_PTR(c->context);
+
         connection_free(c);
 
         if (arg_exit_idle_time < USEC_INFINITY && set_isempty(context->connections)) {