Print templates sometimes silently fail to save

[Benjamin Kalish]

The expected behavior:

If a print template cannot be saved, a warning should be displayed. If a template can be saved, but there is reason to think it might be a mistake, a confirmation should be displayed, explaining the concern and giving the user the option of continuing or cancelling.

The actual behavior:

Print templates sometimes silently fail to save without warning. The user does not know that the save operation did not succeed.

This appears to always be the case when saving an empty print template. To reproduce:
- Open the print template editor (eg/staff/admin/workstation/print/templates)
- Navigate to a template of your choice
- Delete the contents of the template is the textarea (or replace it with whitespace)
- Select Save Locally
- Reload the print template editor and return to the template—you will see that your changes have not been saved.

A workaround for folks that need an empty template is to include only an HTML comment.
An enhancement that would do away with need for empty templates would be to include a NULL printer in the Force Printer Context menu. (Indeed, this would be better than empty templates for most if not all purposes.)

[Benjamin Kalish (bkalish)]

I've created a separate entry for the enhancement that would add a NULL printer to the Force Printer Context menu: https://bugs.launchpad.net/evergreen/+bug/1891550