I ran into this (or something that looks the same) today.
Steps to reproduce
- From the dashboard, click “create a new goal”
- Click “Add progress manually”
- Click “Do more”
- Open a link from the page in a new tab. eg “Help Docs” (I use ctrl+click for this)
- Fill required fields and click “continue”
Able to continue goal creation
Error banner “Today’s weight is required” appears. I could work around by going back using Beeminder’s back button and selecting “Do more” again.
If I skip step 4 it works fine. (I have too many tabs open now!). I’m using Firefox 79.0 under linux.