[PGPRO-2355] Check pathman readiness in split and merge range parts.

Author: arssher

src/pl_range_funcs.c

@@ -489,6 +489,9 @@ split_range_partition(PG_FUNCTION_ARGS)
 	char			   *query;
 	int					i;
 
+	if (!IsPathmanReady())
+		elog(ERROR, "pg_pathman is disabled");
+
 	if (!PG_ARGISNULL(0))
 	{
 		partition1 = PG_GETARG_OID(0);
@@ -652,6 +655,9 @@ merge_range_partitions(PG_FUNCTION_ARGS)
 	FmgrInfo			finfo;
 	int					i;
 
+	if (!IsPathmanReady())
+		elog(ERROR, "pg_pathman is disabled");
+
 	/* Validate array type */
 	Assert(ARR_ELEMTYPE(arr) == REGCLASSOID);