Equations involving cat and slice operators not flattened by the NF

[casella]

Please check ​PowerSystems.Examples.AC1ph_DC.Elementary.DoublelLine. The following error is reported:

[OpenModelica/OMCompiler/Compiler/SimCode/SimCodeUtil.mo:5544:7-5544:48:writable] Error: 
Internal error for Eqn: 1 :
 lineF.C * $DER.lineF.v + {{0.0, -0.0}, {-0.0, 0.0}} * lineF.v = cat(2, lineF.i[:,1:lineF.nF - 2] - lineF.i[:,2:lineF.nF - 1], lineF.i[:,lineF.nF - 1:lineF.nF] - lineF.i[:,lineF.nF:lineF.nF + 1] - lineF.iF_p, lineF.i[:,lineF.nF + 1:3] - lineF.i[:,lineF.nF + 2:4])
array equations currently only supported on form v = functioncall(...)

It seems that for some reason there are equations in a for loop which are not fully unrolled by the NF.

[casella]

Now the same model fails during NFSimplifyModel.simplify giving

Error: Internal error Instantiation of PowerSystems.Examples.AC1ph_DC.Elementary.DoublelLine
failed with no error message