IllegalArgumentException: Additional prepend event after prepend state is done

with version "3.0.0-alpha08"

How to reproduce afaik:

with a PagingSource which can provide more elements than PagerConfig.maxSize,
1. scroll down more items than maxSize,
2. scroll up until a load needs to happen:

`java.lang.IllegalArgumentException: Additional prepend event after prepend state is done
at androidx.paging.SeparatorState.onInsert(Separators.kt:221)
at androidx.paging.SeparatorState.onEvent(Separators.kt:173)
at androidx.paging.SeparatorsKt$insertEventSeparators$$inlined$map$1$2.emit(Collect.kt:135)
at androidx.paging.PagingDataKt$map$$inlined$transform$1$2.emit(Collect.kt:136)
at kotlinx.coroutines.flow.FlowKt__ChannelsKt.emitAllImpl$FlowKt__ChannelsKt(Channels.kt:58)
at kotlinx.coroutines.flow.FlowKt__ChannelsKt$emitAllImpl$1.invokeSuspend(Unknown Source:11)
at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:56)
at kotlinx.coroutines.EventLoop.processUnconfinedEvent(EventLoop.common.kt:69)
at kotlinx.coroutines.DispatchedTaskKt.resumeUnconfined(DispatchedTask.kt:185)
at kotlinx.coroutines.DispatchedTaskKt.dispatch(DispatchedTask.kt:108)
at kotlinx.coroutines.CancellableContinuationImpl.dispatchResume(CancellableContinuationImpl.kt:308)
at kotlinx.coroutines.CancellableContinuationImpl.completeResume(CancellableContinuationImpl.kt:395)
at kotlinx.coroutines.channels.AbstractChannel$ReceiveElement.completeResumeReceive(AbstractChannel.kt:872)
at kotlinx.coroutines.channels.ArrayChannel.offerInternal(ArrayChannel.kt:83)
at kotlinx.coroutines.channels.AbstractSendChannel.send(AbstractChannel.kt:133)
at androidx.paging.PageFetcherSnapshot.doLoad(PageFetcherSnapshot.kt:487)
at androidx.paging.PageFetcherSnapshot$doLoad$1.invokeSuspend(Unknown Source:12)
at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:56)
at android.os.Handler.handleCallback(Handler.java:883)
at android.os.Handler.dispatchMessage(Handler.java:100)
at android.os.Looper.loop(Looper.java:214)
at android.app.ActivityThread.main(ActivityThread.java:7356)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)`

Is it possible to provide a CoroutineContext that catches these exceptions so the app does not crash but we can report them?

Workaround: setting `PagerConfig.maxSize = Int.MAX_VALUE` but it defeats the purpose of using the paging library for infinite lists.

Start with Separators.kt around SeparatorState.onInsert and onEvent, then inspect the load path at PageFetcherSnapshot.kt:487. Reproduce using a PagingSource whose data exceeds PagerConfig.maxSize, scroll down past the limit, and scroll back up; done means the reported prepend failure is handled without the app crash or the underlying paging error is fixed.

Written by the indexing model from the issue text.