What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)
fixes a null reference error
What is the current behavior? (You can also link to an open issue here)
browser shows null reference on navigator which isn't defined if a browser doesn't have access to service workers
What is the new behavior (if this is a feature change)?
null check before reference
Does this PR introduce a breaking change? (What changes might users need to make in their application due to this PR?)
no
fixes a null reference error
What is the current behavior? (You can also link to an open issue here) browser shows null reference on navigator which isn't defined if a browser doesn't have access to service workers
What is the new behavior (if this is a feature change)?
null check before reference
Does this PR introduce a breaking change? (What changes might users need to make in their application due to this PR?) no
Other information: no