When a utility node has a numerical parent, the inference throws a null pointer exception

[Miguel Ángel Artaso Landa]

When there is a network where a utility node has among its parents a numerical variable, the inference is not performed and a null pointer exception is thrown.

[Miguel Ángel Artaso Landa]

When a numeric variable is parent of a utility node, the maximum and minimum possible values of the utility node cannot be calculated if there is no evidence; therefore, in this case we will set this range to (-inf, +inf).

[Miguel Ángel Artaso Landa]

Commit https://bitbucket.org/cisiad/org.openmarkov.core/commits/c4f62e2fc37790aba632abc8e0ccaf80ed897526