ZF-7177: When ZendPDF::save() exits due to fatal error/exception, PDF file is erased

Description

Zend_PDF::save() should gracefully degrade on failure - leaving the PDF unchanged. Instead the PDF is made empty and filesize is zero.

To Reproduce: Use the files in issue #ZF-7176 - after reproducing that bug, the file is destroyed.

Comments

Still an issue in 1.10.3