C# unexpectedly wraps errors in System.Reflection.TargetInvocationException

[jdonaldson]

This is really tough to minimize, but occasionally the C# target will throw an error that is a wrapped version of the one I expect. Specifically, it looks like this wrapper is used.

I've boiled the behavior down to a test case, which I'll link shortly.

[jdonaldson]

Well, this turns out to be difficult to reproduce. I can't get it to fail using the Haxe test runner, only the old unit test version. Here's a standalone repro:

-main RunTests.hx
-cp src
-cp tests
-cp ../hx3compat/std/ # link to the old hx3compat test runner.
-cmd mono bin/test/bin/RunTests.exe
-cs bin/test

package ;
import haxe.unit.*;


class RunTests {
  static function main() {
    var r = new TestRunner();
    r.add(new WrappedError());
    trace(r.run() ? 0 : 500);
  }

}

class WrappedError extends haxe.unit.TestCase {
    public function testWrappedError(){
        var api = new TestApi();
        try{
            Runner.run(api);
            trace("the above should throw an error");
            assertTrue(false);
        } catch (e : Error) {
            trace(e + " is the value for e");
            var res = switch(e){
                case Expected : true;
                default : false;
            }
            assertTrue(res);
            trace("The catch block should have caught an expected error type, instead we got:\n" + e);
            assertTrue(false);
        }
    }

}



class TestApi extends Api<Dynamic> {
    // Suspicious : If I remove this dummy function, the test passes
    public function dummy()  { }

    // Suspicious : If I remove this override, the test passes
    override public function exec( params: Dynamic)  : String {
        throw Expected;
        return 'hi';
    }

}

// Suspicious : If I drop this irrelevant Dynamic parameter, the test passes.
class Api<Dynamic> {

    public function new(){ }

    public function exec( params: Dynamic)  : String {
        throw Expected;
        return 'hi';
    }
}

class Runner{
    public static function run( api : Api<Dynamic>) {
        api.exec(null);
    }

}

enum Error {
	Expected;
}