Support try/catch about dart_eval HOT 3 CLOSED

Indeed, exception handling in general is not really supported yet in dart_eval. I haven't yet had a chance to write down my thoughts on this yet, so I'll put everything here that I believe needs to be done to get this to work:

• Annotate values with runtime type sets at function & field boundaries
• Support runtime type-tests (ie. the is keyword)
• Catch all errors at bridge entry boundaries in the runtime
• Add a catch stack with runtime-type annotated entries, and bytecode ops to push/pop to/from the catch stack
• Add bridge bindings for Exception and StackTrace
• Add a bytecode throw op that iterates backwards through the call, scope, and catch stacks, appending scope entries to the stack trace until it a ) finds a bridge exit boundary, at which point it will actually throw or b) finds a matching catch boundary, at which point it will resume program execution there with the synthesized stack trace
• Support try/catch and throw in the compiler, including for statement flow analysis
• (later) support rethrow in the compiler
• (later) support the Never type somehow
• (later) line number annotation data for stack traces

As you can probably tell, this is kind of a massive undertaking which is why I've been putting it off. It's definitely high on my list of priorities though!

from dart_eval.

Partial support added in v0.6.0. Leaving this open until the implementation is spec-compliant.

from dart_eval.

Closing as this is effectively complete in v0.7.0, including rethrow. Still may need some minor tweaks and fixes in later versions.

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