Fix is to track the state of encountering error in the `Parser` struct and set it to true whereever/whenever
we encounter an error. And the beginning of the next() we return `Ok(None)` to signal to `FallibleIterator` that we should stop parsing.
Fixes https://github.com/tursodatabase/limbo/issues/865
I noticed that the parse errors were a bit hard to read - only the nearest token and the line/col offsets were printed.
I made a first attempt at improving the errors using [miette](https://github.com/zkat/miette).
- Added derive for `miette::Diagnostic` to both the parser's error type and LimboError.
- Added miette dependency to both sqlite3_parser and core. The `fancy` feature is only enabled for CLI.
Some future improvements that can be made further:
- Add spans to AST nodes so that errors can better point to the correct token. See upstream issue: https://github.com/gwenn/lemon-rs/issues/33
- Construct more errors with offset information. I noticed that most parser errors are constructed with `None` as the offset.
Comparisons.
Before:
```
❯ cargo run --package limbo --bin limbo database.db --output-mode pretty
...
limbo> selet * from a;
[2025-01-05T11:22:55Z ERROR sqlite3Parser] near "Token([115, 101, 108, 101, 116])": syntax error
Parse error: near "selet": syntax error at (1, 6)
```
After:
```
❯ cargo run --package limbo --bin limbo database.db --output-mode pretty
...
limbo> selet * from a;
[2025-01-05T12:25:52Z ERROR sqlite3Parser] near "Token([115, 101, 108, 101, 116])": syntax error
× near "selet": syntax error at (1, 6)
╭────
1 │ selet * from a
· ▲
· ╰── syntax error
╰────
```
