When trying to add a new transaction without entering a value in the amount field, an "Operation failed" error appears. The error text should clarify why the transaction failed. Currently, the error is generic and doesn't explain that an amount is required.

Also, the "Add" button gets stuck in an endless loading state. It should be possible to correct this after the error displays, without having to refresh the page, so that you don't have to re-enter the transaction again.