As of version 24.0.201, the UniversalSQL editor shows more context when an error message is displayed as visible in the image below:
Operation is now similar to the on-premises Invantive Query Tool.
New to the Cloud SQL editor is the hint, in this case:
Possible valid alternatives: q[start_date].
It also automatically searches for existing topics on the forums that deal with the same subject. In this case, another relevant message was found.