createAnalytics method in factory throws InvalidArgumentException when no user-agent set

[JunkMyFunk]

Injecting this service into another service causes the createAnalytics() method to be called, which accesses the request stack to get the User-Agent header. In the case this is not set (which often happens with requests from bots or 3rd party API callbacks) an exception is thrown. Since this happens when the services are instantiated, it's hard to handle gracefully.

Passing an empty string to the setUserAgentOverride() method does not throw an exception, only a null value does. Since the user-agent isn't required by the GAMP API anyway, it seems this method should not be called in the constructor or gracefully handle a null value.

[foaly-nr1]

Thanks @JunkMyFunk. Are you happy to open a pull request?