Missing diagram (only showing the legend) on plots with multiple series

[Dexterp37]

Issue Summary

Opening this query should show a plot with multiple series. However, this recently stopped working: the plot is no longer displayed, but the data is still there (from the table view).

It's not showing the plot in Firefox on Windows. The funny thing is that, if I open the Firefox dev tools, the legend promptly goes to the right and shows a mini diagram

Steps to Reproduce

1. Open the query
2. Check the "Fenix Error Counts" tab

Technical details:

• Redash Version: Version: 8.0.0+b5971-m26 (e3d836f)
• Browser/OS: Windows 10
• How did you install Redash: Mozilla sql.telemetry.mozilla.org