HTML parser crash: HTML_BOGUS cast failure on '<' character in text content #8363
Description
Environment
- Biome version: 2.3.8
- Node.js version: v25.2.1
- OS: macOS Darwin 25.1.0 (darwin-arm64)
Description
When running biome check on HTML files, Biome crashes with an internal error when it encounters a < character followed by a number in text content (e.g., <12 months).
While Biome correctly identifies this as a parse error (it expects < to start a tag), the internal handling causes a thread panic with HTML_BOGUS cast failure.
Error Message
Biome encountered an unexpected error
This is a bug in Biome, not an error in your code, and we would appreciate it if you could report it to https://github.com/biomejs/biome/issues/ along with the following information to help us fixing the issue.
Source Location: /Users/runner/work/biome/biome/crates/biome_rowan/src/ast/mod.rs:206:13
Thread Name: biome::workspace_worker_0
Message: Tried to cast node with kind HTML_BOGUS as "biome_html_syntax::generated::nodes::HtmlRoot" but was unable to cast
Minimal Reproduction
Create a file test.html:
<!DOCTYPE html>
<html lang="en">
<head>
<title>Test</title>
</head>
<body>
<div>Target <12 months</div>
</body>
</html>Run:
npx @biomejs/biome check test.htmlThe parse error is expected (Biome interprets <12 as an invalid tag start), but the crash with HTML_BOGUS cast failure should not occur.
Expected Behavior
Biome should report the parse error gracefully without crashing. The error message for the parse issue is fine:
test.html:7:17 parse ━━━━━━━━━━━━━━━━━━━━━━━━
× Expected an attribute but instead found '<'.
> 7 │ <div>Target <12 months</div>
│ ^
But after reporting this, it should continue processing without the internal HTML_BOGUS cast failure.
Additional Context
- The error occurred multiple times (4 times in my case) when running on a directory with multiple HTML files containing similar patterns
- No
biome.jsonconfiguration file was present (default settings) - The
<followed by a number pattern (like<12) is common in content discussing metrics, comparisons, or mathematical expressions