I recently spent some time digging into RxJava’s error handling facilities and realized that throwables forwarded to RxJavaPlugins.setErrorHandler() are sometimes wrapped in OnErrorNotImplementedException and sometimes in UndeliverableException . I couldn’t easily figure out why and when so I drafted a piece of code that I hope might help others shed some light on the matter.

Exceptions can occur in many places in an RxJava chain but for this specific article we will cover three particular situations:

1) Upstream exceptions

Exceptions coming from upstream (i.e. from the source we are hooking up to) are forwarded to the subscriber’s onError() if present, or wrapped in…

Two things happened recently:

• My laptop’s battery was draining out too fast.
• I began learning TypeScript.

I’m using tsc (TypeScript’s compiler) in watch mode which is very convenient to trigger automatic transpilation while developing.

But here’s what happens:

Lately I’m running more and more into an infamous macOS bug whereas the Dock.app somehow hangs leaving the macOS GUI in a semi-stuck state in which, depending on the odds, you might find yourself unable to:

• Launch Mission Control (either via keyboard or hot corner).
• Launch any app from the dock (sometimes clicking and holding on a dock icon does bring up the contextual menu though the menu itself doesn’t react to any clicks whatsoever).
• Launch Spotlight (either via keyboard shortcut or by clicking its icon in the menu bar).
• Force quit any app (pressing CMD-ALT-ESC will bring up the…