Two different crashes in RealmState.RemoveRealm

[eyadon]

We have reverted from 0.82.1 back to 0.80.0 again. :(

The triggering page is a listview of composite display objects assembled from RealmObjects coming from two different realms (one is event records, the other is associated reusable text).

Crash occurs on iOS and Android. The InvalidOperation will happen when scrolling the page, the NRE will happen occasionally on opening the page.

System.NullReferenceException: Object reference not set to an instance of an object.
at Realms.Realm+RealmState+c__AnonStorey2.<>m__0 (System.WeakReference r) [0x00000] in :0
at System.Linq.Enumerable.SingleOrDefault[TSource] (System.Collections.Generic.IEnumerable1[T] source, System.Func2[T,TResult] predicate) [0x00044] in /Users/builder/data/lanes/3511/501e63ce/source/mono/mcs/class/referencesource/System.Core/System/Linq/Enumerable.cs:1122
at Realms.Realm+RealmState.RemoveRealm (Realms.Realm realm) [0x0000d] in :0
at Realms.Realm.Dispose (System.Boolean disposing) [0x0000c] in :0
at Realms.Realm.Finalize () [0x00000] in :0

System.InvalidOperationException: Collection was modified; enumeration operation may not execute.
at System.ThrowHelper.ThrowInvalidOperationException (System.ExceptionResource resource) [0x00000] in /Users/builder/data/lanes/3511/501e63ce/source/mono/mcs/class/referencesource/mscorlib/system/throwhelper.cs:99
at System.Collections.Generic.List1+Enumerator[T].MoveNextRare () [0x00016] in /Users/builder/data/lanes/3511/501e63ce/source/mono/mcs/class/referencesource/mscorlib/system/collections/generic/list.cs:1180 at System.Collections.Generic.List1+Enumerator[T].MoveNext () [0x00050] in /Users/builder/data/lanes/3511/501e63ce/source/mono/mcs/class/referencesource/mscorlib/system/collections/generic/list.cs:1174
at System.Linq.Enumerable.SingleOrDefault[TSource] (System.Collections.Generic.IEnumerable1[T] source, System.Func2[T,TResult] predicate) [0x00052] in /Users/builder/data/lanes/3511/501e63ce/source/mono/mcs/class/referencesource/System.Core/System/Linq/Enumerable.cs:1124
at Realms.Realm+RealmState.RemoveRealm (Realms.Realm realm) [0x0000d] in :0
at Realms.Realm.Dispose (System.Boolean disposing) [0x0000c] in :0
at Realms.Realm.Finalize () [0x00000] in :0

[nirinchev]

Hi @eyadon, I have had trouble reproducing the bug. I have some ideas what might be causing it, but would like to verify that my assumptions are correct. Do you think it would be possible to share your project privately?

[eyadon]

Sure. I'll send an email.

[nirinchev]

Great - I've pushed what I believe should be a fix to that problem, but I'll wait for your project to validate that both issues are gone.

[nirinchev]

Fixed in #1222