gt_ensure uses err about genometools

[gordon]

It was designed that way to simplify the unit tests. The error object should always be called err and gt_ensure should only be used in unit tests. The behaviour is fully documented in the developer guide. Therefore, I don't see this as an issue. But if it really bugs you, please submit a pull requests that changes the code and the developer guide accordingly. Otherwise, please close the issue.

[Garonenur]

It came up while I was writing tests myself and was wondering why I had to add 'had_err' as a parameter but not 'err'.
If its supposed to be as simple as possible I would even remove 'had_err' from the macro and document this in the developer guide.

[gordon]

Sounds great! had_err seems to be used consistently in the unit tests.