Solution "D:\a\HashTableRx\HashTableRx\src\HashTableRx.sln" has active build configurations for the build project. Either enable SuppressBuildProjectCheck on "Build.Solution" or remove the following entries from the solution file: " - {5A3634B0-A15E-4B5D-8367-7D9FD0EACEE2}.PreRelease|Any CPU.Build.0 = Release|Any CPU"

D:\a\HashTableRx\HashTableRx\src\HashTableRx\HashTable.cs(140,13): warning CS8619: Nullability of reference types in value of type 'IObservable<(string, object x)>' doesn't match target type 'IObservable<(string key, object? value)>'. [D:\a\HashTableRx\HashTableRx\src\HashTableRx\HashTableRx.csproj::TargetFramework=netstandard2.0]