bug: parse_json_path panics on unterminated double-quoted fields

[MichaelScofield]

Description

jsonb::jsonpath::parse_json_path panics on an unterminated double-quoted field instead of returning a parse error. Reproduced with the published jsonb 0.5.6 release (also observed with 0.4.4).

Minimal reproduction

Cargo.toml:

[package]
name = "jsonb-jsonpath-repro"
version = "0.1.0"
edition = "2024"

[dependencies]
jsonb = { version = "=0.5.6", default-features = false, features = ["databend"] }

src/main.rs:

fn main() {
    let path = r#"$."a"#; // Input is $."a, with no closing double quote.
    println!("{:?}", jsonb::jsonpath::parse_json_path(path.as_bytes()));
}

Run cargo run.

Actual behavior

panicked at .../jsonb-0.5.6/src/jsonpath/parser.rs:159:34:
range start index 3 out of range for slice of length 2

The following inputs were tested independently and all panic:

$."a
"a
$["a

The valid control input $."a" parses successfully.

Expected behavior

Return Err(Error::InvalidJsonPath) for an unterminated quoted field, without panicking. This matters when JSONPath expressions come from user-supplied SQL queries.

Apparent cause

In src/jsonpath/parser.rs, string() scans until a closing double quote or the end of the input. When the closing quote is missing, i reaches input.len(), but the subsequent code can still evaluate &input[i + 1..].

Checking that the closing quote was actually found before building the remaining-input slice should prevent this out-of-bounds access. A regression test should cover unterminated quoted fields, including escaped content, while retaining valid quoted-field behavior.