Pipes refactoring, Fixes in type checker

Test/Demo.Finance.pas

@@ -84,7 +84,6 @@ begin
     // Für den Compiler ist es eine RecordSeries (Typ), zur Laufzeit ein Stream (Wert)
     StaticType := TTypes.CreateRecordSeries(Def);
 
-    // UPDATED: Dokumentation für die Stream-Variable hinzufügen
     Scope.Define(VarName, Stream, StaticType, 'Financial OHLC Data Stream (Time, Open, High, Low, Close, Vol).');
 end;
 
@@ -118,7 +117,7 @@ begin
         raise Exception.CreateFmt('Variable "%s" is a Stream, but not a TRootStream (cannot push manually).', [VarName]);
 
     Stream := TRootStream(Val.AsStream);
-    Def := Stream.Series.Def;
+    Def := Stream.Def;
 
     // --- Simulation ---
     FLastTime := IncMinute(FLastTime, 5);