Update AbstractData.php

Ability to set default return values when a property is not available in the probe results

src/FFMpeg/FFProbe/DataMapping/AbstractData.php

@@ -37,13 +37,17 @@ abstract class AbstractData implements \Countable
      * Returns the property value given its name.
      *
      * @param  string $property
+     * @param  mixed  $default [optional]
      * @return mixed
      *
      * @throws InvalidArgumentException In case the data does not have the property
      */
-    public function get($property)
+    public function get($property, $default = null)
     {
         if (!isset($this->properties[$property])) {
+            if(!is_null($default)){
+                return $default;
+            }
             throw new InvalidArgumentException(sprintf('Invalid property `%s`.', $property));
         }