Fix formatter (#7098)

The replace function can only work on a string, this little tweak will make the formatter not crash the page when the value is changed.

components/input-number/demo/formatter.md

@@ -24,7 +24,7 @@ ReactDOM.render(
   <div>
     <InputNumber
       defaultValue={1000}
-      formatter={value => `$ ${value.replace(/\B(?=(\d{3})+(?!\d))/g, ',')}`}
+      formatter={value => `$ ${value}`.replace(/\B(?=(\d{3})+(?!\d))/g, ',')}
       parser={value => value.replace(/\$\s?|(,*)/g, '')}
       onChange={onChange}
     />