HMA1 with non parametric tabular models: improve the error message

[csala]

Error Description

When HMA1 is used with a non-parametrical model the message that informs the user about the model not being parametric is being wrongly caught on this try/except block and it ends up producing a cryptic error message. See #340.

Steps to reproduce

See #340.

How to Fix

We should modify the except block to let the NonParametricError go up.

Another possibility to consider is to add a control during instantiation to certify that the model is actually parametric before even starting to fit on the data.