Firebase plugin example does not work.

[chimon2000]

When using the example for the firebase plugin, we get the following error from calling logWarning('Hello Warning');

[Firebase/Analytics][I-ACS013002] Event name must contain only letters, numbers, or underscores: Hello Warning
    ga_error_value (_ev) = Hello Warning;
    ga_error_value (_ev) = Hello Warning;
    ga_error_value (_ev) = Hello Warning;

I believe this is due to the fact that the message is passed as an event to firebase analytics.