fix(typescript): prevent type assertions with array brackets or ? from being treated as HTML tags

[KJyang-0114]

Summary

Fixes #4301 - <string[]> (and <string?>) break TypeScript highlighting.

Root Cause

The isTrulyOpeningTag function in src/languages/javascript.js checks various patterns to determine whether a < followed by word characters is an HTML/XML tag or a TypeScript/JavaScript type expression. It handles < (nested generics) and , (generic parameters), but was missing checks for:

• [ — TypeScript type assertions with array notation like <string[]>
• ? — TypeScript non-null assertions like <string?>

When encountering <string[]>, nextChar after the tag name <string is [. Since this wasn't recognized, the function proceeded to look for a closing </string> tag, treating everything after the > as HTML text until it found one.

Fix

Added two new conditions to the isTrulyOpeningTag ignoreMatch check:

1. nextChar === "[" — catches <string[]>, <number[]>, <T[]> directly
2. nextChar === "?" — catches <string?>, <T?> directly

Also added afterMatch regex checks for whitespace variants:

• /^\s*\[\]/ — catches <string []>
• /^\s+\?/ — catches <string ?>

Test Evidence

Before fix:

INPUT: const myVar = <string[]>this.service.invoke();
OUTPUT: <span class="language-xml">&lt;string[]&gt;this.service.invoke();</span>  ← BROKEN

After fix:

INPUT: const myVar = <string[]>this.service.invoke();
OUTPUT: &lt;<span class="hljs-built_in">string</span>[]&gt;<span class="hljs-variable language_">this</span>.<span class="hljs-property">service</span>.<span class="hljs-title function_">invoke</span>();

JSX constructs like <Component /> and real HTML like <div> continue to be correctly highlighted as XML.

Validation

• All 1570 existing tests pass (0 new failures)
• Manually verified: <string[]>, <number[]>, <T[]>, <string?>, <string []> all no longer break highlighting
• JSX: <div>, <Component />, <MyComponent prop=\"val\" /> still correctly highlighted

Risk & Rollback

• Risk: Low — only affects the tag-detection logic in isTrulyOpeningTag, which already had similar ignore patterns for < and ,
• Rollback: Single file (src/languages/javascript.js) revert to previous state
• Affected languages: TypeScript and JavaScript (which extends the same base)