[BUG] Markdown diffs not displayed for specific input

[oshiteku]

Describe the bug

Differences between files are not displayed even though there are actual differences.

To Reproduce

1. Create the following two files:

   a.md

   # (aaa)

   b.md

   # (bbb)

2. Run diffsitter to compare the files:

   $ diffsitter a.md b.md
   a.md -> b.md
   ============

3. Observe that no differences are displayed.

Expected behavior

The tool should display the differences between the two files, but no output is shown.

Log output/screenshots

output with the --debug flag:

Details

 2025-02-19T16:35:40.412Z DEBUG diffsitter > Checking if a.md can be parsed
 2025-02-19T16:35:40.412Z INFO  libdiffsitter::parse > Deduced language "markdown" from extension "md" from default mappings
 2025-02-19T16:35:40.412Z DEBUG diffsitter           > Deduced language markdown for path a.md
 2025-02-19T16:35:40.412Z DEBUG diffsitter           > Checking if b.md can be parsed
 2025-02-19T16:35:40.412Z INFO  libdiffsitter::parse > Deduced language "markdown" from extension "md" from default mappings
 2025-02-19T16:35:40.412Z DEBUG diffsitter           > Deduced language markdown for path b.md
 2025-02-19T16:35:40.412Z DEBUG libdiffsitter        > Reading a.md to string
 2025-02-19T16:35:40.412Z INFO  libdiffsitter        > Will deduce filetype from file extension
 2025-02-19T16:35:40.412Z INFO  libdiffsitter::parse > Deduced language "markdown" from extension "md" from default mappings
 2025-02-19T16:35:40.412Z INFO  libdiffsitter::parse > Using tree-sitter parser for language markdown
 2025-02-19T16:35:40.412Z INFO  libdiffsitter::parse > Succeeded loading grammar for markdown
 2025-02-19T16:35:40.412Z DEBUG libdiffsitter::parse > Parsed AST
 2025-02-19T16:35:40.412Z INFO  TimerFinished        > parse::parse_file(), Elapsed=50.598µs
 2025-02-19T16:35:40.412Z DEBUG libdiffsitter        > Reading b.md to string
 2025-02-19T16:35:40.412Z INFO  libdiffsitter        > Will deduce filetype from file extension
 2025-02-19T16:35:40.412Z INFO  libdiffsitter::parse > Deduced language "markdown" from extension "md" from default mappings
 2025-02-19T16:35:40.412Z INFO  libdiffsitter::parse > Using tree-sitter parser for language markdown
 2025-02-19T16:35:40.412Z INFO  libdiffsitter::parse > Succeeded loading grammar for markdown
 2025-02-19T16:35:40.412Z DEBUG libdiffsitter::parse > Parsed AST
 2025-02-19T16:35:40.412Z INFO  TimerFinished        > parse::parse_file(), Elapsed=18.165µs
 2025-02-19T16:35:40.412Z INFO  TimerFinished        > ast::from_ts_tree(), Elapsed=3.47µs
 2025-02-19T16:35:40.412Z INFO  TimerFinished        > ast::process(), Elapsed=11.218µs
 2025-02-19T16:35:40.412Z INFO  TimerFinished        > ast::from_ts_tree(), Elapsed=1.646µs
 2025-02-19T16:35:40.412Z INFO  TimerFinished        > ast::process(), Elapsed=4.014µs
 2025-02-19T16:35:40.412Z INFO  TimerFinished        > diff::compute_edit_script(), Elapsed=3.949µs
 2025-02-19T16:35:40.412Z INFO  libdiffsitter::render::unified > Using stack style horizontal for title
a.md -> b.md
============

Platform:

• OS: Ubuntu 24.04
• diffsitter version: 0.8.4

[oshiteku]

This issue doesn't seem to depend on parentheses.

The same problem occurs even with simple inputs that include symbols like comparisons between a? and b?.