Sometimes * column is nan instead of 0

[inodb]

It seems like this is causing another bug in the val_maf column where values can be 0, 0.0 or nan

|---------+-------+-----------+-----+-----+----+----+-----+----+-----+-----+-----+---------+---------+-------------+--------------+-----------------+
|  sample | chrom | pos       | ref | cov | A  | C  | G   | T  | *   | -   | +   | val_ref | val_alt | val_al_type | val_al_count | val_maf         |
|---------+-------+-----------+-----+-----+----+----+-----+----+-----+-----+-----+---------+---------+-------------+--------------+-----------------+
|  AS3T   | X     | 114424753 | G   | 0   | 0  | 0  | 0   | 0  | 0   | nan | nan | G       | A       | snv         | 0            | nan             |
|  AS3T   | 10    | 75567910  | C   | 27  | 0  | 27 | 0   | 0  | 0   | nan | nan | C       | A       | snv         | 0            | 0.0             |
|  AS3T   | 17    | 15468953  | G   | 0   | 0  | 0  | 0   | 0  | nan | nan | nan | G       | A       | snv         | 0            | 0               |