entering $ (dollar sign) in other amount contribution box makes credit card forms go away

Contribution pages only show the payment processor fields if the amount to contribute is more than 0.

However, if a user enters an "other amount" but precedes the amount with a dollar sign (an easy mistake to make), then CiviCRM perceives the values as not being a number and therefore doesn't show the payment processor fields.

The impression from the user perspective is that something is broken because they can't enter their credit card and there is no useful user feedback.

If we silently remove the dollar sign in our calculation, all proceeds properly.