Top runtime issues

Create standard Dictionary class that doesn't throw a KeyNotFoundException

api-suggestion area-System.Collections

Consider creating an IndexSet Type

api-suggestion area-System.Collections

System.Text.Json: Serializing IDictionary with nullable value type throws "Specified method is not supported."

area-System.Text.Json bug

IgnoreNullValues does not work with non-nullable value types

area-System.Text.Json bug json-functionality-doc

Disposing the FileSystemWatcher does not close associated file descriptors

area-System.IO os-mac-os-x

CultureInfo.ClearCachedData may not fully clear if called concurrently with GetCultureInfo

area-System.Globalization bug

System.Net.Mail.Tests.SmtpClientTest.TestZeroTimeout hangs in CI

area-System.Net

System.Text.Json read-only property deserialization API enhancement

api-suggestion area-System.Text.Json

API suggestion: Provide an overload of float/double.ToString that allow precision greater than 99

api-approved area-System.Numerics up-for-grabs

System.Text.Json : Failing at JsonDocument.Parse(json: fullName)

area-System.Text.Json question