From T168371#3530967:
When the user is logged out the editCount will be null [1], which is then passed as the property of the user object [2] to getEditCountBucket [3]. I suggest we either adjust the signature of exports.getEditCountBucket to accept null or pass in a -1 as before.
[1] https://github.com/wikimedia/mediawiki-extensions-Popups/blob/master/src/actions.js#L68
[2] https://github.com/wikimedia/mediawiki-extensions-Popups/blob/master/src/actions.js#L84
[3] https://github.com/wikimedia/mediawiki-extensions-Popups/blob/master/src/reducers/eventLogging.js#L29