Do not crash on Subdirectory when missing Component Directory attribute

Fixes 7407

src/wix/WixToolset.Core/Compiler.cs

@@ -2254,8 +2254,7 @@ private void ParseComponentElement(XElement node, ComplexReferenceParentType par
             {
                 this.Core.Write(ErrorMessages.ExpectedAttribute(sourceLineNumbers, node.Name.LocalName, "Directory"));
             }
-
-            if (!String.IsNullOrEmpty(subdirectory))
+            else if (!String.IsNullOrEmpty(subdirectory))
             {
                 directoryId = this.Core.CreateDirectoryReferenceFromInlineSyntax(sourceLineNumbers, directoryId, subdirectory);
             }

src/wix/test/WixToolsetTest.CoreIntegration/ComponentFixture.cs

@@ -34,12 +34,41 @@ public void CanDetectDuplicateComponentGuids()
                 });
 
                 var errors = result.Messages.Where(m => m.Level == MessageLevel.Error);
-                Array.Equals(new[]
+                Assert.Equal(new[]
                 {
                     369,
                     369
                 }, errors.Select(e => e.Id).ToArray());
             }
         }
+
+        [Fact]
+        public void CannotBuildMissingDirectoryAttributeWithSubdirectory()
+        {
+            var folder = TestData.Get(@"TestData");
+
+            using (var fs = new DisposableFileSystem())
+            {
+                var baseFolder = fs.GetFolder();
+                var intermediateFolder = Path.Combine(baseFolder, "obj");
+                var msiPath = Path.Combine(baseFolder, "bin", "test.msi");
+
+                var result = WixRunner.Execute(new[]
+                {
+                    "build",
+                    Path.Combine(folder, "Component", "MissingDirectoryWithSubdirectory.wxs"),
+                    Path.Combine(folder, "ProductWithComponentGroupRef", "Product.wxs"),
+                    "-bindpath", Path.Combine(folder, "SingleFile", "data"),
+                    "-intermediateFolder", intermediateFolder,
+                    "-o", msiPath
+                });
+
+                var errors = result.Messages.Select(m => m.ToString()).ToArray();
+                WixAssert.CompareLineByLine(new[]
+                {
+                    "The Component/@Directory attribute was not found; it is required."
+                }, errors);
+            }
+        }
     }
 }

src/wix/test/WixToolsetTest.CoreIntegration/TestData/Component/MissingDirectoryWithSubdirectory.wxs

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Wix xmlns="http://wixtoolset.org/schemas/v4/wxs">
+    <Fragment>
+        <ComponentGroup Id="ProductComponents">
+            <Component Subdirectory="fails\without\Directory\attribute">
+                <File Source="test.txt" />
+            </Component>
+        </ComponentGroup>
+    </Fragment>
+</Wix>