[lehni]

Description

Fixes #11445

printSymbol() used String(val), which throws TypeError: Cannot convert a Symbol value to a string for boxed symbols (Object(Symbol('a'))). They reach it through the [object Symbol] branch of printBasicValue(). Using Symbol.prototype.toString.call(val) works for both primitive and boxed symbols.

Regression from #9609 (v5): boxed symbols formatted fine with loupe in v4.

Added a boxed symbol test to test/unit/test/pretty-format.test.ts. It fails without the fix and passes with it.

AI-assisted (Claude Code).

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