Worked on the dream-num/univer repository to enhance the stability of the Formula Engine by addressing a critical runtime bug. Focused on the sheets subsystem, the developer implemented a defensive programming approach using TypeScript, introducing optional chaining to safely access the functionNode when evaluating isFunctionExecutorArgumentsIgnoreNumberPattern. This change prevented potential crashes during function argument evaluation, particularly in edge cases where the functionNode might be undefined. The solution improved code reliability and maintainability, ensuring that future enhancements to the Formula Engine would be less prone to similar issues. The work demonstrated careful attention to runtime stability and robust TypeScript practices.