fix null values becoming empty objects (#26)

lib/util.js

@@ -46,7 +46,7 @@ function convert(obj, conversionFn, newObject) {
 	}
 
 	Object.keys(obj).forEach((prop) => {
-		if (typeof obj[prop] === 'object') {
+		if (typeof obj[prop] === 'object' && obj[prop]) {
 			const convertObj = newObject[conversionFn(prop)] = {};
 			convert(obj[prop], conversionFn, convertObj);
 		} else {

lib/util.spec.js

@@ -140,6 +140,18 @@ describe('util methods', () => {
 			});
 		});
 
+		it('should work with a null value', () => {
+			expect(util.convert({
+				top_prop: {
+					middle_prop: null
+				}
+			}, util.underscoreToCamel)).toEqual({
+				topProp: {
+					middleProp: null
+				}
+			});
+		});
+
 		it('should work with both top and nested properties', () => {
 			expect(util.convert({
 				top_prop: {