Configure bundle dir before fetching catalogues

[Guite]

This fixes the problem that catalogues are read from the "main" translation directory when extracting messages only for a specific bundle. The effect of this change is that messages from the main configuration are not entirely copied into the bundle being processed.

The second commit fixes another problem: when using the YAML format it may happen that the initial translation is null instead of an empty string. The createMessage() method expects a string argument though.

[odolbeau]

Hi @Guite & thanks for your first contribution! 🎉

Could you please split your PR?
I would like to approve your first commit but the second one is not enough to solve the problem you have as the createMessage method won't accept a null argument.

[odolbeau]

PR to split

[Guite]

as the createMessage method won't accept a null argument

This is exactly the problem; hence my fix changes it to a string.

[odolbeau]

as the createMessage method won't accept a null argument

This is exactly the problem; hence my fix changes it to a string.

Oups! :o
In this case, that's perfect, thanks a lot! 👍