gateway-express, when the underlying seneca throws, should pass the error to Express

[lilsweetcaligula]

https://github.com/senecajs/seneca-gateway-express/blob/main/src/gateway-express.ts#L23

When this issue is addressed, then the user's Express error handler will be able to run as normal. Otherwise it is impossible to handle errors without resorting to sorcery.

[lilsweetcaligula]

Currently, whenever a Seneca instance throws an error that I would like to handle, I cannot do that. For example, in my Express app, I would like to catch all act_not_found errors and respond with 404 HTTP. Instead when I send a request to my app, like so:

$ curl $LOCALHOST:9000/api -d '{ "hello": "world", "does": "not_exit" }' -H 'content-type: application/json'

I get 200 HTTP and a payload like this:

{
  error$: true,
  seneca$: true,
  code$: 'act_not_found'
}

[kierandesmond]

Maybe with custom error handling (middleware) you could intercept the Seneca errors and handle them accordingly. 404 response makes sense.