confd: fix annoying warning in log

This fixes the annoying libyang warning after commit da29771.

    confd[3375]: libyang[0]: Invalid argument ctx_node (lyd_find_xpath()).

This happens when the diff is used in the wrong event when it is NULL.

Signed-off-by: Joachim Wiberg <[email protected]>

Author: troglobit

src/confd/src/infix-dhcp-server.c

@@ -300,9 +300,6 @@ int infix_dhcp_server_change(sr_session_ctx_t *session, struct lyd_node *config,
 	int enabled = 0, added = 0, deleted = 0;
 	sr_error_t err = 0;
 
-	if (!lydx_get_xpathf(diff, CFG_XPATH))
-		return SR_ERR_OK;
-
 	switch (event) {
 	case SR_EV_DONE:
 		break;
@@ -312,6 +309,9 @@ int infix_dhcp_server_change(sr_session_ctx_t *session, struct lyd_node *config,
 		return SR_ERR_OK;
 	}
 
+	if (!lydx_get_xpathf(diff, CFG_XPATH))
+		return SR_ERR_OK;
+
 	global = lydx_get_descendant(config, "dhcp-server", NULL);
 	enabled = lydx_is_enabled(global, "enabled");