Prefer warning instead of print message

[HansOlsson]

To me these print-messages starting with "Warning: " should be replaced by assertion-warnings.

[HansOlsson]

Seems to be an issue with CI.

[HansOlsson]

Looking more I realize that the det(L)>=epsilon test for singularity isn't good in general (for several reasons including performance, and scaling). I don't know if the matrices are small enough and normal inductance close enough to 1 that it works well enough.

[henrikt-ma]

Looking more I realize that the det(L)>=epsilon test for singularity isn't good in general (for several reasons including performance, and scaling). I don't know if the matrices are small enough and normal inductance close enough to 1 that it works well enough.

This is a good point, but outside the scope of this PR (which I believe is about getting rid of calls to Streams.print where a warning level assertion makes more sense). Opening a separate issue for a discussion of what do to instead would be a good start.