Address PR review comments

Author: bclothier

Rubberduck.CodeAnalysis/Inspections/Concrete/AssignmentNotUsedInspection.cs

@@ -39,6 +39,7 @@ protected override IEnumerable<IInspectionResult> DoGetInspectionResults()
                 var tree = _walker.GenerateTree(parentScopeDeclaration.Context, variable);
 
                 var references = tree.GetIdentifierReferences();
+                // ignore set-assignments to 'Nothing'
                 nodes.AddRange(references.Where(r =>
                     !(r.Context.Parent is VBAParser.SetStmtContext setStmtContext &&
                     setStmtContext.expression().GetText().Equals(Tokens.Nothing))));

Rubberduck.CodeAnalysis/Inspections/Concrete/FunctionReturnValueNotUsedInspection.cs

@@ -75,6 +75,7 @@ private bool IsRecursive(Declaration function)
 
         private bool IsReturnValueUsed(Declaration function)
         {
+            // TODO: This is O(MG) at work here. Need to refactor the whole shebang.
             return (from usage in function.References
                 where !IsLet(usage)
                 where !IsSet(usage)

Rubberduck.VBEditor.VBA/SafeComWrappers/Application/AccessApp.cs

@@ -28,7 +28,7 @@ public AccessApp(IVBE vbe) : base(vbe, "Access", true)
             });
         }
 
-        public HostDocument GetDocument(QualifiedModuleName moduleName)
+        public override HostDocument GetDocument(QualifiedModuleName moduleName)
         {
             try
             {

Rubberduck.VBEditor.VBA/SafeComWrappers/Application/FallbackApp.cs

@@ -1,4 +1,5 @@
 using System.Collections.Generic;
+using System.Linq;
 using Rubberduck.VBEditor.SafeComWrappers.Abstract;
 
 // ReSharper disable once CheckNamespace - Special dispensation due to conflicting file vs namespace priorities
@@ -8,14 +9,14 @@ public sealed class FallbackApp : IHostApplication
     {
         public FallbackApp(IVBE vbe) { }
         public string ApplicationName => "(unknown)";
-        public IEnumerable<HostDocument> GetDocuments() => null;
+        public IEnumerable<HostDocument> GetDocuments() => Enumerable.Empty<HostDocument>();
         public HostDocument GetDocument(QualifiedModuleName moduleName)
         {
             return null;
         }
         public bool CanOpenDocumentDesigner(QualifiedModuleName moduleName) => false;
         public bool TryOpenDocumentDesigner(QualifiedModuleName moduleName) => false;
-        public IEnumerable<HostAutoMacro> AutoMacroIdentifiers => null;
+        public IEnumerable<HostAutoMacro> AutoMacroIdentifiers => Enumerable.Empty<HostAutoMacro>();
         public void Dispose() { }
     }
 }