ddeboer/data-import — pull request #96 by gries (2014-07-15 12:57:13+00:00)
Title: Fixed php-error "undefined offset" when adding an item-convert and multiple mappings

A php error was thrown:

Undefined offset: 0

when adding a CallbackItemConverter and after that adding multiple mappings:

```php
$workflow->addItemConverter(new CallbackItemConverter(function($item) {
return $item;
}));

$workflow
->addMapping('foo', 'bar') // works
->addMapping('baz', 'bazzoo') // breaks
;
```
This is caused by the **getMappingItemConverter** method which accesses $converters with an index 0 instead of current
```php
$converters = \array_filter(
$this->itemConverters,
function ($converter) {
return $converter instanceof MappingItemConverter;
}
);

if (count($converters) > 0) {
// this breaks because the MappingItemConverter is located at "1"
// because array_filter preservers the keys
$converter = $converters[0];
}
```