Ensure consistent type in ternary for C# compilation

Author: mwilliamson

src/main/java/org/zwobble/mammoth/internal/docx/DisabledFileReader.java

@@ -4,6 +4,10 @@
 import java.io.InputStream;
 
 public class DisabledFileReader implements FileReader {
+    public static final FileReader INSTANCE = new DisabledFileReader();
+
+    private DisabledFileReader() {}
+
     @Override
     public InputStream getInputStream(String uri) throws IOException {
         throw new IOException("could not open external image '" + uri + "': external file access is disabled");

src/main/java/org/zwobble/mammoth/internal/docx/DocumentReader.java

@@ -34,8 +34,8 @@ public static InternalResult<Document> readDocument(
         ContentTypes contentTypes = readContentTypes(zipFile);
 
         FileReader fileReader = externalFileAccess
-            ? new PathRelativeFileReader(path)
-            : new DisabledFileReader();
+            ? PathRelativeFileReader.relativeTo(path)
+            : DisabledFileReader.INSTANCE;
 
         PartWithBodyReader partReader = new PartWithBodyReader(zipFile, contentTypes, fileReader, numbering, styles);
         return InternalResult.flatMap(

src/main/java/org/zwobble/mammoth/internal/docx/PathRelativeFileReader.java

@@ -8,9 +8,13 @@
 import java.util.Optional;
 
 public class PathRelativeFileReader implements FileReader {
+    public static FileReader relativeTo(Optional<Path> path) {
+        return new PathRelativeFileReader(path);
+    }
+
     private final Optional<Path> path;
 
-    public PathRelativeFileReader(Optional<Path> path) {
+    private PathRelativeFileReader(Optional<Path> path) {
         this.path = path;
     }