Add some missing `| undefined` in parser.ts (#17407)
Add some missing `| undefined` in parser.ts (#17407)


nojvek/TypeScript,kitsonk/TypeScript,microsoft/TypeScript,microsoft/TypeScript,minestarks/TypeScript,Microsoft/TypeScript,synaptek/TypeScript,nojvek/TypeScript,alexeagle/TypeScript,synaptek/TypeScript,nojvek/TypeScript,TukekeSoft/TypeScript,kpreisser/TypeScript,SaschaNaz/TypeScript,kpreisser/TypeScript,kpreisser/TypeScript,Eyas/TypeScript,minestarks/TypeScript,RyanCavanaugh/TypeScript,synaptek/TypeScript,Eyas/TypeScript,donaldpipowitch/TypeScript,basarat/TypeScript,basarat/TypeScript,TukekeSoft/TypeScript,kitsonk/TypeScript,donaldpipowitch/TypeScript,basarat/TypeScript,RyanCavanaugh/TypeScript,synaptek/TypeScript,donaldpipowitch/TypeScript,alexeagle/TypeScript,minestarks/TypeScript,nojvek/TypeScript,SaschaNaz/TypeScript,Eyas/TypeScript,alexeagle/TypeScript,basarat/TypeScript,donaldpipowitch/TypeScript,Microsoft/TypeScript,Microsoft/TypeScript,RyanCavanaugh/TypeScript,microsoft/TypeScript,TukekeSoft/TypeScript,weswigham/TypeScript,SaschaNaz/TypeScript,weswigham/TypeScript,Eyas/TypeScript,SaschaNaz/TypeScript,kitsonk/TypeScript,weswigham/TypeScript