type_group may not be a string but an array

[horde3d]

In my installation I stumbled over an issue, were type_group was an array which result in strpos throwing an error because it expects a string.

solr-php-ui/src/templates/view.preview.php

Line 454 in 4e9ce94

<?php if ( $type == 'CSV row' || strpos($type_group, 'Knowledge graph') === 0 || strpos($type, 'Knowledge graph') === 0 ) {

Without further investigations I fixed it by adding a check for is_string

<?php if ( $type == 'CSV row' || (is_string($type_group) && strpos($type_group, 'Knowledge graph') === 0) || strpos($type, 'Knowledge graph') === 0 )