Fix crash when serializing the return type of a generic call to Array.prototype.flat - #38904

Fix crash when serializing the return type of a generic call to Array.prototype.flat#38904

Wesley Wigham (weswigham) merged 4 commits into

microsoft:mastermicrosoft/TypeScript:masterfrom

weswigham:fix-arrayflat-crashweswigham/TypeScript:fix-arrayflat-crashCopy head branch name to clipboard