The color picker doesn't open if the list of configured colors doesn't contain only hex codes

Follow this steps to reproduce:

1. Go to the wiki administration, WYSIWYG editor section
2. Increase the number of rows of the color palette
3. Leave some of the colors from the new row unspecified (the color will be "transparent")
4. Save and edit a page WYSIWYG mode
5. Try to change the text of background color: the color picker doesn't open.