While logged out click on a main menu item (say, the home button) and you'll get the following message in the console:
Validation error against schema MobileWebMainMenuClickTracking: Wrong type for property: username null
According to the schema the username can be empty[1]. We should not send the username if it's null.
[1] https://meta.wikimedia.org/wiki/Schema:MobileWebMainMenuClickTracking
Change 183321 had a related patch set uploaded (by Bmansurov):
Conform to schema
Change 184006 had a related patch set uploaded (by Kaldari):
Conform to schema
Change 184007 had a related patch set uploaded (by Kaldari):
Conform to schema
I attempted to do this, earnestly, but found it a bit worrying so I talked to Ori and some researchers. Ori and I are in agreement that this feature is not as good of an idea as analytics-eng originally thought. One way to handle this would be to implement jsonschema union types (as opposed to just simple types we're using now), which would look something like this:
"type": ["boolean", "null"]
or
"type": ["string", "null"]
But that would require some dev work and we figure people would not be very likely to use it. For now, I'm going to pause work on this task and recommend that we keep null handling the way it is.