$data was never initialized. Although not strictly required by PHP, it is generally a good practice to add $data = array(); before regardless.
Adding an explicit array definition is generally preferable to implicit array
definition as it guarantees a stable state of the code.
Let’s take a look at an example:
foreach($collectionas$item){$myArray['foo']=$item->getFoo();if($item->hasBar()){$myArray['bar']=$item->getBar();}// do something with $myArray}
As you can see in this example, the array $myArray is initialized the first
time when the foreach loop is entered. You can also see that the value of the
bar key is only written conditionally; thus, its value might result from a
previous iteration.
This might or might not be intended. To make your intention clear, your code
more readible and to avoid accidental bugs, we recommend to add an explicit
initialization $myArray=array() either outside or inside the foreach loop.
It seems like the type of the argument is not accepted by the function/method which you are calling.
In some cases, in particular if PHP’s automatic type-juggling kicks in this might be fine. In other cases, however this might be a bug.
We suggest to add an explicit type cast like in the following example: