[Paging with Network] Fix consumeAsFlow can be collected just once

[eneim]

The issue

Currently, the Paging with Network demo uses ReceiveChannel.consumeAsFlow which crashes the App on configuration changes. The reason, IMO, is when the Activity is recreated, the ViewModel's posts value starts collecting again for the new Adapter. This goes against the contract of consumeAsFlow which allows up to one consumer.

How to reproduce:

• Open the PagingWithNetwork sample, choose any of the demos, I picked the "NETWORK ONLY (BY ITEM)".
• After the first loading finishes, rotate the device -> It crashes. Stack trace is as below:

    Process: com.android.example.paging.pagingwithnetwork, PID: 21282
    java.lang.IllegalStateException: ReceiveChannel.consumeAsFlow can be collected just once
        at kotlinx.coroutines.flow.ChannelAsFlow.markConsumed(Channels.kt:125)
        at kotlinx.coroutines.flow.ChannelAsFlow.collect(Channels.kt:150)
        at com.android.example.paging.pagingwithnetwork.reddit.ui.SubRedditViewModel$$special$$inlined$map$1.collect(SafeCollector.common.kt:114)
        at kotlinx.coroutines.flow.internal.ChannelFlowMerge$collectTo$$inlined$collect$1$lambda$1.invokeSuspend(Merge.kt:67)
        at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
        at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:56)
        at androidx.lifecycle.DispatchQueue.drainQueue(DispatchQueue.kt:76)
        at androidx.lifecycle.DispatchQueue.resume(DispatchQueue.kt:55)
        at androidx.lifecycle.LifecycleController$observer$1.onStateChanged(LifecycleController.kt:40)
        at androidx.lifecycle.LifecycleRegistry$ObserverWithState.dispatchEvent(LifecycleRegistry.java:361)
        at androidx.lifecycle.LifecycleRegistry.forwardPass(LifecycleRegistry.java:300)
        at androidx.lifecycle.LifecycleRegistry.sync(LifecycleRegistry.java:339)
        at androidx.lifecycle.LifecycleRegistry.moveToState(LifecycleRegistry.java:145)
        at androidx.lifecycle.LifecycleRegistry.handleLifecycleEvent(LifecycleRegistry.java:131)
        at androidx.lifecycle.ReportFragment.dispatch(ReportFragment.java:68)
        at androidx.lifecycle.ReportFragment$LifecycleCallbacks.onActivityPostCreated(ReportFragment.java:170)
        at android.app.Activity.dispatchActivityPostCreated(Activity.java:1216)
        at android.app.Activity.performCreate(Activity.java:7821)
        at android.app.Activity.performCreate(Activity.java:7801)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1307)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3298)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3462)
        at android.app.ActivityThread.handleRelaunchActivityInner(ActivityThread.java:5429)
        at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:5337)
        at android.app.servertransaction.ActivityRelaunchItem.execute(ActivityRelaunchItem.java:69)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2063)
        at android.os.Handler.dispatchMessage(Handler.java:107)
        at android.os.Looper.loop(Looper.java:214)
        at android.app.ActivityThread.main(ActivityThread.java:7615)
        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:964)

The fix

This PR use the ReceiveChannel.receiveAsFlow instead. It allows multiple receivers.

[dlam]

Thanks for this!