fix(pillarbox-monitoring): inconsistent error name value

Fixes #283, by modifying the value of the error name sent, allowing clearer
errors when consumed by other tools.

This modification supports the properties as defined by the WHATWG as well as
the two custom properties provided by video.js which are `MEDIA_ERR_CUSTOM`
and `MEDIA_ERR_ENCRYPTED`.

- add a static method for setting the value of the error name
- add mock for `MediaError`

Author: amtins

src/trackers/PillarboxMonitoring.js

@@ -246,7 +246,7 @@ class PillarboxMonitoring {
       log: JSON
         .stringify(error.metadata || pillarbox.log.history().slice(-15)),
       message: error.message,
-      name: error.code,
+      name: PillarboxMonitoring.errorKeyCode(error.code),
       ...playbackPosition,
       url
     });
@@ -815,6 +815,25 @@ class PillarboxMonitoring {
     };
   }
 
+  /**
+   * Returns a string representing the error key combined with its error code.
+   *
+   * If the error code doesn't exist the error key undefined.
+   *
+   * @param {number} code The error code
+   *
+   * @returns {string} The error key combined with its error code
+   */
+  static errorKeyCode(code) {
+    const error = [
+      'MEDIA_ERR_CUSTOM',
+      ...Object.keys(window.MediaError),
+      'MEDIA_ERR_ENCRYPTED'
+    ];
+
+    return `${error[code]}: ${code}`;
+  }
+
   /**
    * Generates a new session ID.
    *

test/trackers/pillarbox-monitoring.spec.js

@@ -7,6 +7,7 @@ describe('PillarboxMonitoring', () => {
   let monitoring;
 
   global.navigator.sendBeacon = jest.fn();
+  global.window.MediaError = jest.fn().mockReturnValue({  });
 
   beforeEach(() => {
     player = playerMock();