This bug found by @Urbanecm.
Steps to Reproduce:
Open up a production Wikipedia. Save an edit on a page in the article namespace. Go to your newcomer homepage. Click the link in the impact module for that article's pageviews (the link labeled "--").
Actual Results:
The "--" is a link that tries to open up the Pageviews Analysis tool, which tries to open with a "from" date after the "to" date. This spins for a couple minutes and then errors out. That bug with the Pageviews Analysis tool is filed at T222403.
Expected Results:
The "--" should not be a link at all, because there are no pageviews to see yet. We want to convey to the newbie that they should check back tomorrow for pageviews, but we haven't come up with a good design for that yet (T216220).
Note: this is important to fix before turning on the experiment on May 6.