Invalid format strings no longer crash applications

Double.ToString(format), Integer.ToString(format), and DateTime.ToString(format) along with their locale overloads pass an invalid user-supplied format string such as D2 on a Double straight through to .NET. .NET throws System.FormatException, which escapes the VM and is reported by the desktop host as a fatal VM exception, terminating the application with exit code 1. Invalid format strings must instead raise a normal, source-mapped, catchable Objo InvalidArgumentException so an application can present a friendly error instead of crashing.