Solved sonar code smell (Merged if statements), removed System.Collections.Immutable and implemented promise state cleanup (#24)

Author: rstaib

src/Benchmark.Tests/Benchmark.Tests.csproj

@@ -11,7 +11,6 @@
   <ItemGroup>
     <PackageReference Include="BenchmarkDotNet" Version="0.11.1" />
     <PackageReference Include="Moq" Version="4.9.0" />
-    <PackageReference Include="System.Collections.Immutable" Version="1.5.0" />
   </ItemGroup>
 
   <ItemGroup>

src/Core/Core.csproj

@@ -21,8 +21,4 @@
     <DebugType>pdbonly</DebugType>
     <DebugSymbols>true</DebugSymbols>
   </PropertyGroup>
-
-  <ItemGroup>
-    <PackageReference Include="System.Collections.Immutable" Version="1.5.0" />
-  </ItemGroup>
 </Project>

src/Core/DataLoaderBase.cs

@@ -150,13 +150,12 @@ public Task<TValue> LoadAsync(TKey key)
 
                 if (_options.Batching)
                 {
-                    if (!_buffer.TryAdd(resolvedKey, promise))
-                    {
-                        if (_buffer.TryGetValue(resolvedKey,
+                    if (!_buffer.TryAdd(resolvedKey, promise) &&
+                        _buffer.TryGetValue(resolvedKey,
                             out TaskCompletionSource<TValue> value))
-                        {
-                            promise = value;
-                        }
+                    {
+                        promise.TrySetCanceled();
+                        promise = value;
                     }
                 }
                 else