Ignoring line with invalid Entrez_Id NA

[forus]

According to the documentation, one or both of Hugo_Symbol, Entrez_Gene_Id can be specified.

However, if you miss Entrez_Gene_Id the loader will produce a warning per each row in the CNA data file.

Warnings / Errors:
-------------------
0.  Ignoring line with invalid Entrez_Id NA; 20x

Despite the message, records get loaded to the database:

-> records inserted into `sample_cna_event` table: 1720

Expected behavior: The loader won't show a warning when there is no Entrez_Gene_Id column specified.

The issue in the code:
If there is no entrez id column, entrezAsString will be assigned to "NA" here
The warning gets generated few lines below here

Proposed solution: check entrezAsString for NA and return 0 without warning in this case.