Validation error at /civicrm/admin/contribute/amount requires either that at least on Contribution Label be set or that "Allow other amounts" be checked

To reproduce, create a new Contribution Page. On the Contribution Amounts page, enter a few Fixed Contribution Options with valid amounts and empty labels, and make sure to leave "Allow Other Amounts" unchecked. On submit, you will get this error: If you want to enable the 'Contribution Amounts section', you need to either 'Allow Other Amounts' and/or enter at least one row in the 'Fixed Contribution Amounts' table.

Since it is a perfectly valid use case to want to display only dollar amounts next to radio buttons, and since no other validation was being done on the labels, I've simply removed the references to the label values in the formRule function. The patch file is attached.