`$this->reflClass->name, $embeddable->reflClass->name` cause `PHP Notice:  Trying to get property of non-object` if either of the `reflClass` properties are null. Suggest something like:

    if (! empty($this->embeddedClasses[$property]['columnPrefix'])) {
        $fieldMapping['columnName'] = $this->embeddedClasses[$property]['columnPrefix'] . $fieldMapping['columnName'];
    } else {
        $className = $this->reflClass ? $this->reflClass->name : null;
        $embeddedClassName = $embeddable->reflClass ? $embeddable->reflClass->name : null;
        $fieldMapping['columnName'] = $this->namingStrategy->embeddedFieldToColumnName($property, $fieldMapping['columnName'], $className, $embeddedClassName);
    }