Add expense invalid amount with more than 1 decimal points

[TanLeYang]

When using the add expense command and entering an amount with more than 1 decimal points, e.g 69.1234.1233, the application doesn't add the expense but also does not show any error message.

Reproduction

1. Enter add a/X c/C D/Y d/desc where C, Y and desc are valid but X is a string of digits with more than 1 "."
2. The application will not add the expense nor show any error message.