DbContext.EnsureCreated() : ArgumentNullException only on RELEASE build - sqlite

Question

I am using microsoft ef-core and Sqlite database in my xamarin-forms app. My model is quite big, so I guess it's not a good idea to drop it here. I was working on the app for couple weeks and tested on my phone in Debug mode - everything worked perfectly.
But as soon as I've built RELEASE version - I got ArgumentNullException right on DbContext.EnsureCreated() call. I could find it using console output. So it says:
Value cannot be null. Parameter name: key
On DEBUG build my application works perfectly fine, and I have no build-dependent precompiler directives in my code also. Using Visual Studio 2017
Any thoughts or advices on what can I check?
UPD: here is stacktrace I got in Release:
I/mono-stdout(24851): TRACE: at System.Collections.Generic.Dictionary`2[TKey,TValue].TryInsert (TKey key, TValue value, System.Collections.Generic.InsertionBehavior behavior) [0x00008] in <d029cac6f9824b0bb72d5eb6d48d11f3>:0
I/mono-stdout(24851): at System.Collections.Generic.Dictionary`2[TKey,TValue].Add (TKey key, TValue value) [0x00000] in <d029cac6f9824b0bb72d5eb6d48d11f3>:0
I/mono-stdout(24851): at Microsoft.EntityFrameworkCore.Sqlite.Query.Internal.SqliteDateTimeAddTranslator..ctor (Microsoft.EntityFrameworkCore.Query.ISqlExpressionFactory sqlExpressionFactory) [0x000c5] in <7b7aa88a95d54aa786bada86edd4821a>:0
I/mono-stdout(24851): at Microsoft.EntityFrameworkCore.Sqlite.Query.Internal.SqliteMethodCallTranslatorProvider..ctor (Microsoft.EntityFrameworkCore.Query.RelationalMethodCallTranslatorProviderDependencies dependencies) [0x0001d] in <7b7aa88a95d54aa786bada86edd4821a>:0
I/mono-stdout(24851): at (wrapper managed-to-native) System.Reflection.MonoCMethod.InternalInvoke(System.Reflection.MonoCMethod,object,object[],System.Exception&)
I/mono-stdout(24851): at System.Reflection.MonoCMethod.InternalInvoke (System.Object obj, System.Object[] parameters, System.Boolean wrapExceptions) [0x00005] in <d029cac6f9824b0bb72d5eb6d48d11f3>:0

Answer 1

The reason behind this is that the linker is being overly aggressive and it strips System.DateTime class from mscorlib assembly. The proper fix is, instead of preserveDateTimeMethods solution that you mentioned, to create a Custom Linker Configuration.
Create an empty file LinkDescription.xml
Add it to the OS-level project (Android, iOS, etc).
Set its build action to LinkDescription
Add System.DateTime to the linker block
Here's how:
<?xml version="1.0" encoding="UTF-8" ?>
<linker>
<assembly fullname="mscorlib">
<type fullname="System.DateTime" preserve="methods" />
</assembly>
</linker>

Answer 2

So, I've searched for hours and as soon as I've posted quiestion..
Looks like it's a ef-core bug - a linker problem working with DateTime types leading to attempt of adding null-key value to Dictionary.
Links to bug discussion:
https://github.com/dotnet/efcore/issues/14091
https://github.com/dotnet/efcore/issues/10963
I had this problem on my Android release build, so I've added line of code from one of comments on first discussion.
Added this line in my MainActivity.cs before Xamarin.Forms initialization:
var preserveDateTimeMethods = DateTime.Now.AddYears(1).AddMonths(1).AddDays(1).AddHours(1).AddMinutes(1).AddSeconds(1);
It resolved my problem. Hope it helps somebody.