Error on using Gallery with Wrap

[InvaderX9]

When using a gallery inside of a set to a specific width (in his case, 280px), I get this error at the top of the page for each image in the gallery:

Warning: Array to string conversion in C:\Users\Administrator\Documents\Wiki Database\98 - Judgement Multiverse\dokuwiki\inc\parser\metadata.php on line 620

The images still display, but the big error messages at the top are a little annoying.

[mprins]

seems a duplicate of #198 ; should be fixed after #216