Correctly join command line arguments and other small clean up and optimizations

2 files changed, 2 insertions, 2 deletions

diff --git a/src/WixToolset.Core/CommandLine/CommandLineParser.cs b/src/WixToolset.Core/CommandLine/CommandLineParser.cs
index 017810e0..3c7f3d1e 100644
--- a/src/WixToolset.Core/CommandLine/CommandLineParser.cs
+++ b/src/WixToolset.Core/CommandLine/CommandLineParser.cs
@@ -54,7 +54,7 @@ namespace WixToolset.Core.CommandLine
 
             if (!String.IsNullOrEmpty(context.Arguments))
             {
-                args = CommandLineParser.ParseArgumentsToArray(context.Arguments).Union(args).ToArray();
+                args = CommandLineParser.ParseArgumentsToArray(context.Arguments).Concat(args).ToArray();
             }
 
             return this.ParseStandardCommandLine(context, args);
diff --git a/src/WixToolset.Core/Librarian.cs b/src/WixToolset.Core/Librarian.cs
index 3e843070..f4191e86 100644
--- a/src/WixToolset.Core/Librarian.cs
+++ b/src/WixToolset.Core/Librarian.cs
@@ -143,7 +143,7 @@ namespace WixToolset.Core
 
                 foreach (var tuple in sections.SelectMany(s => s.Tuples))
                 {
-                    foreach (var field in tuple.Fields.Where(f => f.Type == IntermediateFieldType.Path))
+                    foreach (var field in tuple.Fields.Where(f => f?.Type == IntermediateFieldType.Path))
                     {
                         var pathField = field.AsPath();