Error: `Cannot read property removeChild of undefined/null expression`

[dwieringa]

In production, I have Rollbar sometimes reporting Cannot read property removeChild of undefined/null expression from the following line:

SnackBar/src/js/snackbar.js

Line 129 in 507e661

this.parentElement.removeChild(this);

I noticed that the other reference to removeChild first verifies that the parentElement is defined. This one does not.

I don't have time to submit a PR at the moment, but thought I would capture this in case others run into the same thing or someone has time fix.