Fix double free in case of errors when running MI command

(cherry picked from commit ce6e844)

Author: vladpaiu

modules/mi_http/http_fnc.c

@@ -619,7 +619,6 @@ struct mi_root* mi_http_run_mi_cmd(int mod, int cmd, const str* arg,
 				(mi_flush_f *)mi_http_flush_tree, &html_page_data);
 	if (mi_rpl == NULL) {
 		LM_ERR("failed to process the command\n");
-		if (mi_cmd) free_mi_tree(mi_cmd);
 		goto error;
 	} else {
 		*page = html_page_data.page;

modules/mi_json/http_fnc.c

@@ -318,7 +318,6 @@ struct mi_root* mi_json_run_mi_cmd(struct mi_cmd *f, const str* miCmd,
         NULL, &html_page_data);
   if (mi_rpl == NULL) {
     LM_ERR("failed to process the command\n");
-    if (mi_cmd) free_mi_tree(mi_cmd);
     goto error;
   } else {
     *page = html_page_data.page;

modules/mi_xmlrpc_ng/http_fnc.c

@@ -551,7 +551,6 @@ struct mi_root* mi_xmlrpc_http_run_mi_cmd(const str* arg,
 				(mi_flush_f *)mi_xmlrpc_http_flush_tree, &html_page_data);
 	if (mi_rpl == NULL) {
 		LM_ERR("failed to process the command\n");
-		if (mi_cmd) free_mi_tree(mi_cmd);
 		goto xml_error;
 	} else {
 		*page = html_page_data.page;