Improve error reporting for application exceptions thrown in the initialization phase.

[losfair]

Currently, for exceptions thrown in the initialization phase of an application:

1. Stack traces are not included in the error message.
2. The error is not aggregated to Kafka.

For example I got a confusing error message:

2022-01-03T10:15:43.468764Z ERROR blueboat::ctx: native invoke error from app ***.tar] request "unknown": expected type `v8::data::Uint8Array`, got `v8::data::Value`

Due to an undefined being passed to new TextDecoder().decode().