Gus contributed to the tc39/ecma262 repository by addressing a critical bug in ECMAScript class evaluation. Focusing on specification compliance, Gus ensured that the [[SourceText]] internal slot is set on class objects before static blocks are evaluated during class instantiation. This change, implemented in JavaScript with a strong emphasis on ECMAScript specification and language design, aligns the evaluation order and source association with the standard. By resolving this subtle issue in ClassDefinitionEvaluation, Gus improved the reliability and correctness of class initialization semantics across JavaScript engines. The work demonstrates careful attention to detail and a deep understanding of language internals.