eZ\Publish\Core\FieldType\RichText\Type::fromPersistenceValue PHP Method

$fieldValue->data is supposed to be a string.

public fromPersistenceValue ( eZ\Publish\SPI\Persistence\Content\FieldValue $fieldValue ) : Value
$fieldValue	eZ\Publish\SPI\Persistence\Content\FieldValue
return	Value

    public function fromPersistenceValue(FieldValue $fieldValue)
    {
        return new Value($fieldValue->data);
    }

Type