Component used: Paging Version used: 3.0.0-alpha01

I was moving my app over to Paging 3.0.0-alpha01. It uses Room 2.3.0-alpha01 for support for PagingSource.

Dao:

internal abstract val chosenPhotosPaged: PagingSource<Int, ChosenPhoto>

ViewModel:

internal val chosenPhotos = Pager(PagingConfig(24, 12)) {
    GalleryDatabase.getInstance(application).chosenPhotoDao().chosenPhotosPaged
}.flow.cachedIn(viewModelScope)

UI:

lifecycleScope.launchWhenStarted {
    viewModel.chosenPhotos.collect {
        // Load into a PagingDataAdapter
        chosenPhotosAdapter.submitData(it)
    }
}

Steps to reproduce:

Checkout the paging3 branch of Muzei
Add 30+ images to your device
Install and Activate Muzei
Go to the Sources screen and select the "My Photos" source
Accept the runtime permission
Go to the Settings screen
Hit the FAB at the bottom, then the image button
Select ~2-5 images
Rotate your device
Hit the FAB at the bottom, image, and add additional images

Expected behavior: The new images are seamlessly added

Actual behavior: I received the following exception:

2020-06-11 19:54:18.401 net.nurik.roman.muzei E/AndroidRuntime: FATAL EXCEPTION: main
    Process: net.nurik.roman.muzei, PID: 21268
    java.lang.IllegalStateException: cannot collect twice from pager
        at androidx.paging.PageFetcherSnapshot$pageEventFlow$1.invokeSuspend(PageFetcherSnapshot.kt:94)
        at androidx.paging.PageFetcherSnapshot$pageEventFlow$1.invoke(Unknown Source:10)
        at androidx.paging.CancelableChannelFlowKt$cancelableChannelFlow$1.invokeSuspend(CancelableChannelFlow.kt:35)
        at androidx.paging.CancelableChannelFlowKt$cancelableChannelFlow$1.invoke(Unknown Source:10)
        at kotlinx.coroutines.flow.ChannelFlowBuilder.collectTo$suspendImpl(Builders.kt:327)
        at kotlinx.coroutines.flow.ChannelFlowBuilder.collectTo(Unknown Source:0)
        at kotlinx.coroutines.flow.internal.ChannelFlow$collectToFun$1.invokeSuspend(ChannelFlow.kt:53)
        at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
        at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:56)
        at kotlinx.coroutines.EventLoop.processUnconfinedEvent(EventLoop.common.kt:69)
        at kotlinx.coroutines.DispatchedTaskKt.resumeUnconfined(DispatchedTask.kt:184)
        at kotlinx.coroutines.DispatchedTaskKt.dispatch(DispatchedTask.kt:108)
        at kotlinx.coroutines.CancellableContinuationImpl.dispatchResume(CancellableContinuationImpl.kt:308)
        at kotlinx.coroutines.CancellableContinuationImpl.resumeImpl(CancellableContinuationImpl.kt:318)
        at kotlinx.coroutines.CancellableContinuationImpl.resumeWith(CancellableContinuationImpl.kt:250)
        at kotlinx.coroutines.channels.AbstractChannel$ReceiveElement.resumeReceiveClosed(AbstractChannel.kt:877)
        at kotlinx.coroutines.channels.AbstractSendChannel.helpClose(AbstractChannel.kt:312)
        at kotlinx.coroutines.channels.AbstractSendChannel.close(AbstractChannel.kt:241)
        at kotlinx.coroutines.channels.ChannelCoroutine.close(Unknown Source:2)
        at kotlinx.coroutines.channels.SendChannel$DefaultImpls.close$default(Channel.kt:102)
        at androidx.paging.CancelableChannelFlowKt$cancelableChannelFlow$1$1.invoke(CancelableChannelFlow.kt:33)
        at androidx.paging.CancelableChannelFlowKt$cancelableChannelFlow$1$1.invoke(Unknown Source:2)
        at kotlinx.coroutines.InvokeOnCompletion.invoke(JobSupport.kt:1386)
        at kotlinx.coroutines.JobSupport.notifyCompletion(JobSupport.kt:1529)
        at kotlinx.coroutines.JobSupport.completeStateFinalization(JobSupport.kt:323)
        at kotlinx.coroutines.JobSupport.finalizeFinishingState(JobSupport.kt:240)
        at kotlinx.coroutines.JobSupport.tryMakeCompletingSlowPath(JobSupport.kt:903)
        at kotlinx.coroutines.JobSupport.tryMakeCompleting(JobSupport.kt:860)
        at kotlinx.coroutines.JobSupport.cancelMakeCompleting(JobSupport.kt:693)
        at kotlinx.coroutines.JobSupport.cancelImpl$kotlinx_coroutines_core(JobSupport.kt:664)
        at kotlinx.coroutines.JobSupport.cancelInternal(JobSupport.kt:629)
        at kotlinx.coroutines.JobSupport.cancel(JobSupport.kt:614)
        at kotlinx.coroutines.Job$DefaultImpls.cancel$default(Job.kt:164)
        at androidx.paging.PageFetcherSnapshot.close(PageFetcherSnapshot.kt:183)
        at androidx.paging.PageFetcher$flow$1$2.invokeSuspend(PageFetcher.kt:75)
        at androidx.paging.PageFetcher$flow$1$2.invoke(Unknown Source:18)
        at kotlinx.coroutines.flow.FlowKt__TransformKt$scan$$inlined$unsafeFlow$1$lambda$1.emit(Collect.kt:133)
        at kotlinx.coroutines.flow.FlowKt__ChannelsKt.emitAllImpl$FlowKt__ChannelsKt(Channels.kt:58)
        at kotlinx.coroutines.flow.FlowKt__ChannelsKt$emitAllImpl$1.invokeSuspend(Unknown Source:11)
        at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
        at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:56)
        at android.os.Handler.handleCallback(Handler.java:883)
        at android.os.Handler.dispatchMessage(Handler.java:100)
        at android.os.Looper.loop(Looper.java:214)
        at android.app.ActivityThread.main(ActivityThread.java:7356)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)
2020-06-11 19:54:18.407 net.nurik.roman.muzei I/Process: Sending signal. PID: 21268 SIG: 9