Error prompting message is not user-friendly

[bobbai00]

During the editing phase, the error message is not readable by regular users, and can make users panic.

Take this editing for example, users just drag a project operator, but receive an error says "IllegalArgumentException". Although for texera people, we know this error is caused by Project operator having no attributes selected by the user yet. But for new users, it is discouraging to see such error without adding anything to the Project operator yet.

We should definitely improve this experience.

Some thoughts

• UI side: add a warning section to the result panel.
• Message side: wrap the error message: IllegalArgumentException, with more readable message, e.g. Please select at least 1 attribute to project.