stateful
`onDidClose` called twice for interactive cell in gRPC runner execution
As far as I can tell, for an interactive task, the terminal task only closes once onDidClose gets called. If this gets called before vscode starts listening internally (i.e. because the grpc server is down), the terminal task can hang indefinitely.
Unfortunately I don't see a great way to fix this at the moment. I fixed it in #286 by calling _onDidClose after getting an open() callback, but this results in two _onDidClose callbacks.
Probably the solution here is to defer running _onDidClose until open() in an interactive cell. Though this presents potential issues if we want to replace task execution with an embedded terminal down the road.
Regardless, I don't think this is super high priority, and shouldn't cause any issues for users.
