🐞 fix(improve robustness, check input para):

src/plugin/plugin_manager.cpp

@@ -152,6 +152,7 @@ struct plugin_manager_schema *plugin_manager_init(struct stellar *st, const char
 
 void plugin_manager_exit(struct plugin_manager_schema *plug_mgr)
 {
+	if(plug_mgr==NULL)return;
 	struct plugin_specific *p=NULL;
     if (plug_mgr->plugin_load_specs_array)
     {

test/packet_inject/packet_inject.cpp

@@ -428,6 +428,8 @@ static void on_sess_free(struct session *sess, void *sess_ctx, void *plugin_ctx)
 
 static void on_sess_msg(struct session *sess, int topic_id, const void *msg, void *sess_ctx, void *plugin_ctx)
 {
+    if(msg==NULL)return;// session closing, return directly
+
     char buffer[1024] = {0};
     struct packet *pkt = (struct packet *)msg;
     struct plugin_ctx *ctx = (struct plugin_ctx *)plugin_ctx;