<@UHAJKUSTU> I have this piece of code ```runCatching { navigator.pushNew(screen) }.onFailure ...

# decompose

[Vaibhav Jaiswal]

@Arkadii Ivanov I have this piece of code

runCatching { 
    navigator.pushNew(screen) 
}.onFailure {
    if (it.message == "Configurations must be unique") navigator.bringToFront(screen)
}

Now I have screens in backstack like A -> B
Now, if i go from B to A, nothing is happening
And when i press back button while being in B, it goes back to A and the whole UI freezes
and if I press back again, the back stack behaves weirdly,

[Arkadii Ivanov]

There are multiple issues with the code.

1. Navigation exceptions are not supposed to be recoverable. The router may be left in an inconsistent state. We should avoid navigation errors at all costs, and treat them as fatal.
2. In some rare cases the navigation can be performed asynchronously, and so the onFailure callback won't be called at all.
3. The next alpha version of Decompose will introduce pushToFront function, which is probably what you need?
4. In the meantime you can copy it from here.

[Vaibhav Jaiswal]

Thanks a lot

[Vaibhav Jaiswal]

@Arkadii Ivanov would this replace if the same config is at the top of stack or just ignore adding it like pushNew?

[Arkadii Ivanov]

Though, this particular check is currently performed in the very beginning, so I guess it shouldn't cause any issues.

[Arkadii Ivanov]

It will ignore and do nothing. Replacing a config object with another that is equal is essentially a no-op operation.

[Vaibhav Jaiswal]

Okay, thanks

[Arkadii Ivanov]

FYI, pushToFront is released in Decompose 3.0.0-alpha05.