How to reproduce:

1. Open attached project
2. Allow the API Updater to run
- Note an error occurs:
APIUpdater encountered some issues and was not able to finish.

System.NullReferenceException: Object reference not set to an instance of an object
at BooUpdater.BooDocument.FindNext (Boo.Lang.Compiler.Ast.LexicalInfo start, Char c) [0x00000] in <filename unknown>:0
at BooUpdater.LastArgumentPositionResolver.FindPositionAfter (Boo.Lang.Compiler.Ast.LexicalInfo start, Char toBeFound) [0x00000] in <filename unknown>:0
at BooUpdater.LastArgumentPositionResolver.FindPositionAfterClosingParenthesis (Boo.Lang.Compiler.Ast.LexicalInfo start) [0x00000] in <filename unknown>:0
at BooUpdater.LastArgumentPositionResolver.OnMethodInvocationExpression (Boo.Lang.Compiler.Ast.MethodInvocationExpression node) [0x00000] in <filename unknown>:0
at Boo.Lang.Compiler.Ast.MethodInvocationExpression.Accept (IAstVisitor visitor) [0x00000] in <filename unknown>:0
at BooUpdater.LastArgumentPositionResolver.Resolve (BooUpdater.BooDocument document, Boo.Lang.Compiler.Ast.MethodInvocationExpression node) [0x00000] in <filename unknown>:0
at BooUpdater.FixParsedSourceLocations.StartPointFor (BooUpdater.BooDocument document, Boo.Lang.Compiler.Ast.MethodInvocationExpression node) [0x00000] in <filename unknown>:0

- Reproduced in Version 5.4.0b7 (83df6fa5e23f), Version 5.3.2p4 (f3eb2e65f8a2)
- Blocked from testing Version 5.2.4f1 (98095704e6fe) due to script errors