Partial (simplest possible case) fix for OnError GoTo

[GrahamTheCoder]

Partial (simplest possible case) fix for #426

Simplest case covered here: A single top level On Error Go To, everything after it could be placed in a try catch and go to the outer label

May be possible to cover in future

• OnErrorGoTo statement and label in same scope, but not top-level (e.g. nested in an if statment/loop)

• Extend that system to two statements within a scope (e.g. changing the error handler part way through, it would be possible to have a nested try catch block for the second one, and use an filter clause to avoid hitting the outer one

Still no sensible known solution

General solution: The difficulty is that in C# the labels are scoped to the containing block, so it isn't possible to goto a label straight from a catch block. I've therefore created a loop and switch to allow it to re-enter the scope where it's possible to go to the label. That still won't work for labels inside if blocks and I'm still trying to think of a less verbose/ugly way of handling this in general.

Future

The solution may be to make a best effort at converting to working code, but to always spit out a code comment containing the original VB.
It'd also be possible in a comment to add a suggested starting point for a maintainable solution i.e. Just put it in a simple try catch block.

[GrahamTheCoder]

This is the example output - which is what's discouraging me from further work on this...
One other possible avenue might be to use something like DynamicMethod with IL.Emit to get around the restrictions of scopes and jump to labels with less boilerplate.