Prevent ArgumentOutOfRangeException

[brminnick]

Description

This PR fixes a race condition that can happen when the same event is removed in parallel.

Error

System.ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index

Stack Trace

AsyncAwaitBestPractices.EventManagerService.RemoveEventHandler (System.String& eventName, System.Object& handlerTarget, System.Reflection.MemberInfo& methodInfo, System.Collections.Generic.Dictionary`2[System.String,System.Collections.Generic.List`1[AsyncAwaitBestPractices.Subscription]]& eventHandlers) [0x0005c] in <63bee8e7afc14051bfc24f7fd7c5ed2c>:0;
AsyncAwaitBestPracticesAsyncAwaitBestPractices.WeakEventManager.RemoveEventHandler (System.Delegate& handler, System.String& eventName) [0x00035] in <63bee8e7afc14051bfc24f7fd7c5ed2c>:0;AsyncAwaitBestPracticesAsyncAwaitBestPractices.WeakEventManager.RemoveEventHandler (System.Delegate handler, System.String eventName) [0x00000] in <63bee8e7afc14051bfc24f7fd7c5ed2c>:0;AsyncAwaitBestPracticesGitTrends.GitHubAuthenticationService.remove_AuthorizeSessionStarted (System.EventHandler value) [0x00000] in <5bbcdde3e8a94c7aaeae05ae46b1d556>:0;

Reproduction

Parallel.For(0, 10, count => _propertyChangedWeakEventManager.RemoveEventHandler(sampleDelegate, nameof(sampleDelegate)));

static void sampleDelegate(object? sender, EventArgs e)
{
}

Detailed Description

• Adds lock to EventManagerService.RemoveEventHandler and EventManagerService.AddEventHandler
• Adds Unit Test to ensure race condition no longer occurs
• Adds .NET 6 support to Unit Tests
• Adds .NET 5 and .NET 6 Support to Azure Pipelines Build
• Increment to v6.0.3