"notify function called synchronously" message appears when it shouldn't

[vilterp]

The following message shows up for every event after

• a Debug.crash (i.e. a bug in the developer's code)
• an uncaught javascript exception (i.e. a bug in a Native module or a core library such as Array)

When, according to Evan, "That error is only supposed to show up in development if I do something weird (or when someone is doing crazy stuff with Native modules and ports)":

The notify function has been called synchronously!
This can lead to frames being dropped
Definitely report this to <https://github.com/elm-lang/Elm/issues>

Thus, the vast majority of the time this message is inappropriate because it's a bug in your Elm code or a native module, not a bug in the Elm runtime that you should report to core or the compiler.

Perhaps on a Debug.crash or JS exception from a native module, the runtime should print out a message such as "this module has stopped working because of a Debug.crash" or "this module has stopped working because of a native module exception" once, and then go into a crashed state in which it doesn't process any more events or print out any more messages.

[rtfeldman]

This can also happens when JS code being invoked via a port crashes, which happens a lot in my line of work. 😉

Unfortunately I've had trouble reproducing it minimally, but one way to reliably reproduce it is:

1. Check out the repro-notify branch of Dreamwriter (which induces a runtime exception in a port)
2. Build it.
3. Click "new chapter" (the big plus sign in the lower left) twice.

The first time you click it, it will error out with "Uncaught Error: kaboom!" but subsequent clicks will result in notify being triggered synchronously.

[rtfeldman]

This can also happens when JS code being invoked via a port crashes, which happens a lot in my line of work. 😉

Unfortunately I've had trouble reproducing it minimally, but one way to reliably reproduce it is:

1. Check out the repro-notify branch of Dreamwriter (which induces a runtime exception in a port)
2. Build it.
3. Click "new chapter" (the big plus sign in the lower left) twice.

The first time you click it, it will error out with "Uncaught Error: kaboom!" but subsequent clicks will result in notify being triggered synchronously.

[evancz]

There is no such thing as a notify function anymore with 0.17, so it's resolved by removing signals.

[evancz]

There is no such thing as a notify function anymore with 0.17, so it's resolved by removing signals.