(chocolatey#3258) Expand logging for nuget resources errors

Previously all that was logged was the surface exception, which in quite
a few cases we've seen not yielding any useful information.

Instead, log the entire exception chain, surfacing just the outermost
and innermost exceptions, which we generally expect to contain the most
relevant information for users.

src/chocolatey/ExceptionExtensions.cs

@@ -0,0 +1,21 @@
+namespace chocolatey
+{
+    using System;
+    using System.Collections.Generic;
+    using System.Linq;
+    using System.Text;
+    using System.Threading.Tasks;
+
+    public static class ExceptionExtensions
+    {
+        public static IEnumerable<Exception> Enumerate(this Exception error)
+        {
+            while (error != null)
+            {
+                yield return error;
+
+                error = error.InnerException;
+            }
+        }
+    }
+}

src/chocolatey/chocolatey.csproj

@@ -200,6 +200,7 @@
       <Link>Properties\SolutionVersion.cs</Link>
     </Compile>
     <Compile Include="AssemblyExtensions.cs" />
+    <Compile Include="ExceptionExtensions.cs" />
     <Compile Include="infrastructure.app\attributes\MultiServiceAttribute.cs" />
     <Compile Include="infrastructure.app\commands\ChocolateyCacheCommand.cs" />
     <Compile Include="infrastructure.app\commands\ChocolateyListCommand.cs" />
@@ -538,4 +539,4 @@
   <Target Name="AfterBuild">
   </Target>
   -->
-</Project>
+</Project>

src/chocolatey/infrastructure.app/nuget/NuGetEndpointResources.cs

@@ -153,7 +153,32 @@ private T ResolveResource<T>()
             {
                 if (!_resolvingFailed)
                 {
-                    this.Log().Warn(ex.InnerException.Message);
+                    // Unwrap the AggregateException as its surface message is useless
+                    Exception error = ex.InnerException;
+                    this.Log().Warn(error.Message);
+
+                    // Enumerate the inner exceptions, log all but the last one in the list to debug
+                    string message = null;
+                    foreach (var err in error.InnerException.Enumerate())
+                    {
+                        if (message != null)
+                        {
+                            this.Log().Debug(message);
+                        }
+
+                        message = err.Message;
+                        error = err;
+                    }
+
+                    // If the last error in the list isn't the only one, write its message as a warning.
+                    // Typically the deepest/last error in the InnerExceptions will be a relevant and
+                    // actionable error.
+                    if (error != ex.InnerException && message != null)
+                    {
+                        this.Log().Warn(message);
+                    }
+
+                    this.Log().Warn("For more information on this issue and guidance in resolving the problem, see https://ch0.co/t/svcidx");
                     _resolvingFailed = true;
                 }
             }