Flinn-X bdb3a2ded7 fix(webui): handle undefined language in code blocks
When fenced code blocks have no language specifier, react-syntax-highlighter
receives undefined for the language prop, causing a white screen crash.

- CodeBlock.tsx: fallback to 'text' when language is undefined
- MarkdownTextRenderer.tsx: defensive fallback at fence rendering site
- Added test cases for both components

Fixes #4116
2026-05-31 15:42:40 +08:00
..