add null check for better testability

[ataraxus]

Short description of what this resolves:

Better testability.

Changes proposed in this pull request:

• add null check to prevent null dereference while testing with karma

Ionic Version: 2.x / 3.x

Fixes: #11185

[Mridul16]

where should i put the null check code? in test case or the component? Also if in the test case then where should i write it in the test case as i am not even able to create the page instance?.