Made config parameter on Config object optional

Author: Ashleigh

src/__tests__/config.spec.ts

@@ -52,4 +52,8 @@ describe('Config object', () => {
       }),
     ).toEqual({ eighth: true });
   });
+
+  it('Can instance without parameters', () => {
+    expect(new Config()).toBeInstanceOf(Config);
+  });
 });

src/config.ts

@@ -7,8 +7,8 @@ export class Config {
   /**
    * @param config
    */
-  constructor(config: {[s: string]: any}) {
-    Object.keys(config).forEach(key => this[key] = config[key]);
+  constructor(config?: {[s: string]: any}) {
+    if (config) Object.keys(config).forEach(key => this[key] = config[key]);
   }
 
   /**