[BUGFIX] avoid execptions while extracting metadata

[franzkugelmann]

when extracting data there might occur exceptions because the extracted data does not fit the validation rules. Improved expression to ensure valid data.

[franzkugelmann]

just saw that you recently tackled one issue by another way: #1. Please consider our pull request as alternative, i think it solves that issue

[franzkugelmann]

by the way, see you in Nuernberg tomorrow :)

[daniellienert]

I think this wouldn't fix the problem as the problem occurs when a tag with an empty name is created.

[franzkugelmann]

It seems that if i.e. iptc.keywords is an empty string, it results in an array with one empty element resulting in the tried creation of a tag with empty name. It fixed the problem in our real live case. But, nevermind, is already solved in your PR!

[daniellienert]

Hey Franz,
Thanks a lot for the PR, but as you mentioned I fixed the problem another way - and I see some issues with your commit (see comments)

[daniellienert]

I'm definitely keen to hear what your real life case is and how we can improve the package. Let's talk about it tomorrow.