Unclear Error message

[brianyiktaktsui]

When there is a missing attribute in the GTC, it will report the missing entry in its numerical representation, it would be nice to report what exactly is missing. For example instead of reporting "GTC converter - ERROR - 1004", it would to nice to report "GTC converter - ERROR - 1004(Missing genotype quality score)"

[jjzieve]

Piggybacking off this issue. Certain assertions when violated don't have a message (e.g. https://github.com/Illumina/GTCtoVCF/blob/develop/BPMRecord.py#L270)
All assertions should ideally have a helpful error message.