Address comments

Author: aibaars

csharp/autobuilder/Semmle.Autobuild.CSharp/StandaloneBuildRule.cs

@@ -12,9 +12,9 @@ public BuildScript Analyse(Autobuilder builder, bool auto)
             BuildScript GetCommand(string? solution)
             {
                 string standalone;
-                if (!(builder.CodeQLExtractorLangRoot is null) && !(builder.CodeQlPlatform is null)) {
+                if (builder.CodeQLExtractorLangRoot is object && builder.CodeQlPlatform is object) {
                     standalone = builder.Actions.PathCombine(builder.CodeQLExtractorLangRoot, "tools", builder.CodeQlPlatform, "Semmle.Extraction.CSharp.Standalone");
-                } else if (!(builder.SemmlePlatformTools is null)) {
+                } else if (builder.SemmlePlatformTools is object) {
                     standalone = builder.Actions.PathCombine(builder.SemmlePlatformTools, "csharp", "Semmle.Extraction.CSharp.Standalone");
                 } else {
                     return BuildScript.Failure;