segmentation fault when using FSILS assembly type in Trilinos implementation

Description

The FSILS type of assembly when using Trilinos library for linear algebra throw a segmentation fault. This is caused by a variable 'nnzPerRow' which was not defined before. The variable 'nnzPerRow' contains how many non-zero elements there are per row and it is used to assemble the global matrix in Trilinos data structure.

Reproduction

Just set the following:
<Linear_algebra type="trilinos" >
fsils
...
</Linear_algebra>
In the input file. A segmentation fault for invalid memory location will be thrown by the solver.

Expected behavior

The expected result is to use either assembly type ('trilinos' or 'fsils') when selecting Trilinos library for the linear algebra.

Additional context

Even though the default and suggested assembly type is 'trilinos', the 'fsils' type is the only option available whenever 'ustruct' type of equation is selected.

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