fix .NET deserialization

src/verse-ref.test.ts

@@ -187,17 +187,27 @@ describe('VerseRef', () => {
     describe('Serialization', () => {
       it('should serialize empty VerseRef', () => {
         const vref = new VerseRef();
-        expect(vref.toJSON()).toEqual({ book: '', chapterNum: 0, verseNum: 0 });
+
+        const json = vref.toJSON();
+
+        expect(json).toEqual({ book: '', chapterNum: 0, verseNum: 0 });
+        // Needed to help .NET deserialization.
+        expect(json).not.toHaveProperty('verse');
       });
 
       it('should serialize VerseRef', () => {
         const vref = new VerseRef(1, 2, 3, ScrVers.Septuagint);
-        expect(vref.toJSON()).toEqual({
+
+        const json = vref.toJSON();
+
+        expect(json).toEqual({
           book: 'GEN',
           chapterNum: 2,
           verseNum: 3,
           versificationStr: 'Septuagint',
         });
+        // Needed to help .NET deserialization.
+        expect(json).not.toHaveProperty('verse');
       });
 
       it('should stringify VerseRef', () => {

src/verse-ref.ts

@@ -484,13 +484,15 @@ export class VerseRef {
   toJSON(): SerializedVerseRef {
     let verse: string | undefined = this.verse;
     if (verse === '' || verse === this.verseNum.toString()) verse = undefined;
-    return {
+    const json = {
       book: this.book,
       chapterNum: this.chapterNum,
       verseNum: this.verseNum,
       verse,
       versificationStr: this.versificationStr,
     };
+    if (!verse) delete json.verse;
+    return json;
   }
 
   /**