Errors are swallowed

[chrismwendt]

https://github.com/sourcegraph/lang-go/blob/70c1fd74e9839ce8251d3dc9f3c640001ccf64b7/src/lang-go.ts#L221-L225

@felixfbecker I'm having some difficulty figuring out why errors are getting swallowed in my rxjs code here. I tried console.logging every Promise and it seems like the Promise rejection gets lost somewhere in:

https://github.com/sourcegraph/lang-go/blob/70c1fd74e9839ce8251d3dc9f3c640001ccf64b7/src/lang-go.ts#L212-L219

But I couldn't figure out why. If you'd like I can share my screen sometime and we can take a look at this.

[felixfbecker]

You manually create an Observable here:

https://github.com/sourcegraph/lang-go/blob/70c1fd74e9839ce8251d3dc9f3c640001ccf64b7/src/lang-go.ts#L183-L193

But in there, I don't see you calling observer.error() in any error condition.
In general I would recommend you to not create Observables manually, try to use operators.

[chrismwendt]

How do I expose unsubscribe when using fromPromise()? I want to make sure that old connections get disposed of when the langserver address changes.

[felixfbecker]

Nvm, I just saw that it actually emits a function that performs the actual request

[felixfbecker]

I don't know just from looking at it. It's hard to follow the data flow from reading

[felixfbecker]

Here's how I would debug this:

• Set a breakpoint or console.error() at the source where the error is triggered, i.e. the WebSocket error event handler.
• When hit, move the log to the next Promise that should have adopted this error (add a .catch(err => console.error('err', err)).
• Move up towards the highest call site until you find the point where the error gets lost.