Fix problem with plans reported by Pavel Zotov.

create table test(id int primary key using index test_id, f01 timestamp);
create index test_f01 on test(f01);
commit;
set term ^;
create procedure sp_test (a_id int) returns (o_f01 type of column test.f01) as
begin
    for
        select f01 from test where id = :a_id plan (test order test_f01)
        into o_f01
    do
        suspend;
end
^

Statement failed, SQLSTATE = 2F000
Error while parsing procedure "PUBLIC"."SP_TEST"'s BLR
-Invalid name:

Author: asfernandes

src/jrd/RecordSourceNodes.cpp

@@ -3702,7 +3702,8 @@ void RseNode::planSet(CompilerScratch* csb, PlanNode* plan)
 	fb_assert(planRelation || planProcedure);
 
 	ObjectsArray<QualifiedMetaString> planAliasList;
-	QualifiedMetaString::parseSchemaObjectListNoSep(planAlias, planAliasList);
+	if (planAlias.hasData())
+		QualifiedMetaString::parseSchemaObjectListNoSep(planAlias, planAliasList);
 
 	const auto name = planRelation ? planRelation->rel_name :
 		planProcedure ? planProcedure->getName() :