fix: app crashes, caused by dragging pager which has no item LazyColumn

[RyuNen344]

Issue

• not exist

Overview (Required)

• HorizontalPager crashes when drag page with zero size content.
• It was occurring in the timetable.

Stacktrace

2021-10-21 01:29:21.230 15258-15258/io.github.droidkaigi.feeder.debug E/AndroidRuntime: FATAL EXCEPTION: main
    Process: io.github.droidkaigi.feeder.debug, PID: 15258
    java.lang.IllegalArgumentException: Layout size for current item is 0
        at com.google.accompanist.pager.PagerState$scrollableState$1.invoke(PagerState.kt:184)
        at com.google.accompanist.pager.PagerState$scrollableState$1.invoke(PagerState.kt:176)
        at androidx.compose.foundation.gestures.DefaultScrollableState$scrollScope$1.scrollBy(ScrollableState.kt:134)
        at androidx.compose.foundation.gestures.ScrollingLogic.dispatchScroll-iGfEq8s(Scrollable.kt:249)
        at androidx.compose.foundation.gestures.ScrollDraggableState.dragBy-Uv8p0NA(Scrollable.kt:323)
        at androidx.compose.foundation.gestures.DraggableKt$draggable$9$2$2.invokeSuspend(Draggable.kt:242)
        at androidx.compose.foundation.gestures.DraggableKt$draggable$9$2$2.invoke(Unknown Source:8)
        at androidx.compose.foundation.gestures.DraggableKt$draggable$9$2$2.invoke(Unknown Source:4)
        at androidx.compose.foundation.gestures.ScrollDraggableState$drag$2.invokeSuspend(Scrollable.kt:334)
        at androidx.compose.foundation.gestures.ScrollDraggableState$drag$2.invoke(Unknown Source:8)
        at androidx.compose.foundation.gestures.ScrollDraggableState$drag$2.invoke(Unknown Source:4)
        at androidx.compose.foundation.gestures.DefaultScrollableState$scroll$2$1.invokeSuspend(ScrollableState.kt:147)
        at androidx.compose.foundation.gestures.DefaultScrollableState$scroll$2$1.invoke(Unknown Source:8)
        at androidx.compose.foundation.gestures.DefaultScrollableState$scroll$2$1.invoke(Unknown Source:4)
        at androidx.compose.foundation.MutatorMutex$mutateWith$2.invokeSuspend(MutatorMutex.kt:160)
        at androidx.compose.foundation.MutatorMutex$mutateWith$2.invoke(Unknown Source:8)
        at androidx.compose.foundation.MutatorMutex$mutateWith$2.invoke(Unknown Source:4)
        at kotlinx.coroutines.intrinsics.UndispatchedKt.startUndispatchedOrReturn(Undispatched.kt:89)
        at kotlinx.coroutines.CoroutineScopeKt.coroutineScope(CoroutineScope.kt:264)
        at androidx.compose.foundation.MutatorMutex.mutateWith(MutatorMutex.kt:153)
        at androidx.compose.foundation.gestures.DefaultScrollableState$scroll$2.invokeSuspend(ScrollableState.kt:145)
        at androidx.compose.foundation.gestures.DefaultScrollableState$scroll$2.invoke(Unknown Source:8)
        at androidx.compose.foundation.gestures.DefaultScrollableState$scroll$2.invoke(Unknown Source:4)
        at kotlinx.coroutines.intrinsics.UndispatchedKt.startUndispatchedOrReturn(Undispatched.kt:89)
        at kotlinx.coroutines.CoroutineScopeKt.coroutineScope(CoroutineScope.kt:264)
        at androidx.compose.foundation.gestures.DefaultScrollableState.scroll(ScrollableState.kt:144)
        at com.google.accompanist.pager.PagerState.scroll(PagerState.kt:645)
        at androidx.compose.foundation.gestures.ScrollDraggableState.drag(Scrollable.kt:332)
        at androidx.compose.foundation.gestures.DraggableKt$draggable$9$2.invokeSuspend(Draggable.kt:239)
        at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
        at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:106)
        at androidx.compose.ui.platform.AndroidUiDispatcher.performTrampolineDispatch(AndroidUiDispatcher.android.kt:81)
        at androidx.compose.ui.platform.AndroidUiDispatcher.access$performTrampolineDispatch(AndroidUiDispatcher.android.kt:41)
        at androidx.compose.ui.platform.AndroidUiDispatcher$dispatchCallback$1.doFrame(AndroidUiDispatcher.android.kt:68)
        at android.view.Choreographer$CallbackRecord.run(Choreographer.java:1035)
        at android.view.Choreographer.doCallbacks(Choreographer.java:845)
        at android.view.Choreographer.doFrame(Choreographer.java:775)
        at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:1022)
        at android.os.Handler.handleCallback(Handler.java:938)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loopOnce(Looper.java:201)
        at android.os.Looper.loop(Looper.java:288)
        at android.app.ActivityThread.main(ActivityThread.java:7842)
        at java.lang.reflect.Method.invoke(Native Method)

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sorry, my captures are very flicking ;(

[takahirom]

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