Check for null pointers in a few more places, avoiding crashes (mostl…

…y with new OpenDSS users)

src/CAPI/CAPI_Transformers.pas

@@ -494,7 +494,7 @@ procedure Transformers_Get_WdgVoltages(var ResultPtr: PDouble; ResultCount: PAPI
 var
     elem: TObj;
 begin
-    if not _activeObj(DSSPrime, elem) then
+    if (not _activeObj(DSSPrime, elem))  or MissingSolution(DSSPrime) then
     begin
         DefaultResult(ResultPtr, ResultCount);
         Exit;
@@ -521,7 +521,7 @@ procedure Transformers_Get_WdgCurrents(var ResultPtr: PDouble; ResultCount: PAPI
     elem: TObj;
     NumCurrents: Integer;
 begin
-    if not _activeObj(DSSPrime, elem) then
+    if (not _activeObj(DSSPrime, elem)) or MissingSolution(DSSPrime) then
     begin
         DefaultResult(ResultPtr, ResultCount);
         Exit;
@@ -594,17 +594,14 @@ procedure Transformers_Get_LossesByType(var ResultPtr: PDouble; ResultCount: PAP
     CResult: PComplexArray; // this array is one-based, see DSSUcomplex
     elem: TObj;
 begin
-    if not _activeObj(DSSPrime, elem) then
+    if (not _activeObj(DSSPrime, elem)) or MissingSolution(DSSPrime) then
     begin
         DefaultResult(ResultPtr, ResultCount);
         Exit;
     end;
 
     DSS_RecreateArray_PDouble(ResultPtr, ResultCount, 2 * 3);
 
-    if not elem.Enabled then
-        Exit;
-
     CResult := PComplexArray(ResultPtr);
     elem.GetLosses(CResult[1], CResult[2], CResult[3]);
     // Keep the results in VA (NOT kVA) for consistency with CktElement_Get_Losses

src/Common/Circuit.pas

@@ -2266,6 +2266,11 @@ function TDSSCircuit.Get_Losses: Complex;
 begin
     // Return total losses in all PD Elements
     Result := 0;
+    if (Solution.NodeV = NIL) then
+    begin
+        Exit;
+    end;
+
     for pdelem in PDElements do
     begin
         if pdelem.enabled then

src/Common/CktElement.pas

@@ -1139,6 +1139,9 @@ procedure TDSSCktElement.ComputeVterminal;
     nref: PInteger;
     nv0, nv: PDouble;
 begin
+    if NodeRef = NIL then 
+        Exit;
+
     vterm := PDouble(VTerminal);
     nref := PInteger(NodeRef);
     nv0 := PDouble(ActiveCircuit.solution.NodeV);

src/PDElements/AutoTrans.pas

@@ -1535,6 +1535,9 @@ procedure TAutoTransObj.GetAllWindingCurrents(CurrBuffer: pComplexArray);
     ITerm_NL: pComplexArray;
 
 begin
+    if (not Enabled) or (NodeRef = NIL) or (ActiveCircuit.Solution.NodeV = NIL) then
+        Exit;
+
     try
         Vterm := Allocmem(SizeOf(Complex) * 2 * NumWindings);
         Iterm := Allocmem(SizeOf(Complex) * 2 * NumWindings);
@@ -1604,6 +1607,9 @@ procedure TAutoTransObj.GetWindingVoltages(iWind: Integer; VBuffer: pComplexArra
 var
     i, ii, k, NeutTerm: Integer;
 begin
+    if (not Enabled) or (NodeRef = NIL) or (ActiveCircuit.Solution.NodeV = NIL) then
+        Exit;
+
     try
         // return Zero if winding number improperly specified
         if (iWind < 1) or (iWind > NumWindings) then
@@ -1669,6 +1675,14 @@ procedure TAutoTransObj.GetLosses(var TotalLosses, LoadLosses, NoLoadLosses: Com
     cTempIterminal: pComplexArray;
     i: Integer;
 begin
+    if (not FEnabled) or (NodeRef = NIL) then
+    begin
+        TotalLosses := 0;
+        LoadLosses := 0;
+        NoLoadLosses := 0;
+        Exit;
+    end;
+
     // Calculates losses in watts, vars
     TotalLosses := Losses;   // Side effect: computes Iterminal
 

src/PDElements/Reactor.pas

@@ -1019,8 +1019,17 @@ procedure TReactorObj.GetLosses(var TotalLosses, LoadLosses, NoLoadLosses: Compl
     i: Integer;
     v: Complex;
 begin
+    if (not FEnabled) or (NodeRef = NIL) then
+    begin
+        TotalLosses := 0;
+        LoadLosses := 0;
+        NoLoadLosses := 0;
+        Exit;
+    end;
+
     // Only report No Load Losses if Rp defined and Reactor is a shunt device;
     // Else do default behavior.
+
     if (RpSpecified and IsShunt and (Rp <> 0.0)) then
     begin
         TotalLosses := Losses;  // Side effect: computes Iterminal and Vterminal

src/PDElements/Transformer.pas

@@ -1583,6 +1583,9 @@ procedure TTransfObj.GetWindingVoltages(iWind: Integer; VBuffer: pComplexArray);
 var
     i, ii, k, NeutTerm: Integer;
 begin
+    if (not Enabled) or (NodeRef = NIL) or (ActiveCircuit.Solution.NodeV = NIL) then
+        Exit;
+
     // return Zero if winding number improperly specified
     if (iWind < 1) or (iWind > NumWindings) then
     begin
@@ -1632,7 +1635,7 @@ procedure TTransfObj.GetLosses(var TotalLosses, LoadLosses, NoLoadLosses: Comple
     cTempIterminal: pComplexArray;
     i: Integer;
 begin
-    if not FEnabled then
+    if (not FEnabled) or (NodeRef = NIL) then
     begin
         TotalLosses := 0;
         LoadLosses := 0;