HTTP 500 When deleting a filter component and reordering

[michaelkoitz]

A report becomes unusable when a filter item is deleted and the list of filter components is reordered.

Steps to reproduce:

1. Create a new Report
2. Add 3 filters
3. Delete the one in position 2 (in the middle)
4. Move the last filter up (click the arrow "up" => "↑" )
5. Click on View Report

Possible fix:
Re-indexing the components array after unsetting element.
after line 108 (unset)

$elements = array_values($elements);