Restrict name list len for domain constraints

This avoids an ugly-looking "cache lookup failure" message.

Ugliness pointed out by Andres Freund.

src/backend/catalog/objectaddress.c

@@ -1534,6 +1534,12 @@ pg_get_object_address(PG_FUNCTION_ARGS)
 	 */
 	switch (type)
 	{
+		case OBJECT_DOMCONSTRAINT:
+			if (list_length(name) < 2)
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+						 errmsg("name list length must be at least %d", 2)));
+			break;
 		case OBJECT_LARGEOBJECT:
 			if (list_length(name) != 1)
 				ereport(ERROR,

src/test/regress/expected/object_address.out

@@ -171,8 +171,8 @@ WARNING:  error for table constraint,{addr_nsp,zwei},{}: relation "addr_nsp" doe
 WARNING:  error for table constraint,{addr_nsp,zwei},{integer}: relation "addr_nsp" does not exist
 WARNING:  error for table constraint,{eins,zwei,drei},{}: schema "eins" does not exist
 WARNING:  error for table constraint,{eins,zwei,drei},{integer}: schema "eins" does not exist
-WARNING:  error for domain constraint,{eins},{}: cache lookup failed for type 0
-WARNING:  error for domain constraint,{eins},{integer}: cache lookup failed for type 0
+WARNING:  error for domain constraint,{eins},{}: name list length must be at least 2
+WARNING:  error for domain constraint,{eins},{integer}: name list length must be at least 2
 WARNING:  error for domain constraint,{addr_nsp,zwei},{}: type "addr_nsp" does not exist
 WARNING:  error for domain constraint,{addr_nsp,zwei},{integer}: type "addr_nsp" does not exist
 WARNING:  error for domain constraint,{eins,zwei,drei},{}: schema "eins" does not exist