Summary:
Since formula errors are typically obtained from the Python data engine, they
were not returning any info for errors in on-demand tables (not loaded into the
data engine). This change implements a detailed message to explain such errors,
mainly to point out that on-demand table is the reason.
Test Plan: Added a check to the OnDemand test that formula error details are shown.
Reviewers: jarek
Reviewed By: jarek
Differential Revision: https://phab.getgrist.com/D4317
5ef54b278f