fixed domains null issue

[manzurahammed]

Changes proposed in this Pull Request:

Closes # .

Replace this with a good description of your changes & reasoning.

Checks:

• Does your code follow the WordPress coding standards?
• N/A Have you written new tests for your changes, as applicable?
• N/A Have you successfully run tests with your changes locally?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changes proposed in this Pull Request:

Youtube video not playing if used Magnific Popup js library to a popup youtube video
if linker.domains inducted by a null value (line number 135 )