Feature: Error Handling Documentation

### Issue

The documentation lacks explanations on the types of errors one can expect, & methods to convey the errors to the users of an editor.

### Solution
The documentation should have a section that describes:
* Error types
* How to handle errors in code
* Suggestions on how to convey the error in the UI

Start by locating the project's documentation structure and existing guidance on errors. Add a section covering error types, handling errors in code, and UI suggestions for conveying errors; the work is done when all three requested topics are documented clearly.

Written by the indexing model from the issue text.