Commands/CalcLaplacian: handle missing incidence matrix.

Author: PMeira

docs/changelog.md

@@ -21,6 +21,7 @@
 
 - Alt/CE: Fix `RegisterValues` in the C header.
 - Alt/PDE: Check for missing solution in a few functions.
+- Commands/`CalcLaplacian`: Give proper error message instead of crashing or giving "access violation" messages.
 
 ## Version 0.14.1 (2024-02-16)
 

src/Executive/ExecCommands.pas

@@ -420,6 +420,11 @@ procedure ProcessCommand({$IFDEF DSS_CAPI_PM}MainDSS{$ELSE}DSS{$ENDIF}: TDSSCont
 {$ENDIF}
             ord(Cmd.CalcLaplacian):
             begin
+                if DSS.ActiveCircuit.Solution.IncMat = NIL then
+                begin
+                    DoSimpleMsg(DSS, _('Indidence matrix is not present. Please run either "CalcIncMatrix" or "CalcIncMatrix_O" first.'), 8877);
+                    Exit;
+                end;
                 with DSS.ActiveCircuit.Solution do
                 begin
                     Laplacian := IncMat.Transpose();          // Transposes the Incidence Matrix