meld subprocess crashes due to "AttributeError: 'NoneType' object has no attribute 'get_path'"

[Karl-Philipp Richter]

Steps to reproduce:

  1. start meld and open an empty comparison, enter "a" in the left and "b" in the right panel
  2. select open file for the right panel and discard changes

When investigated with the `pdb` module the following stack trace is shown:

    Traceback (most recent call last):
      File "/usr/lib/python2.7/dist-packages/meld/filediff.py", line 1776, in on_fileentry_file_set
        paths = [f.get_path() for f in files]
    AttributeError: 'NoneType' object has no attribute 'get_path'

This is not a severe issue and doesn't seem to affect functionality, but triggers `apport`. I assume `meld` still relies on its strange process- (instead of thread-)based architecture.

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: meld 3.12.3-1
Uname: Linux 4.1.1-040101-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.17.2-0ubuntu1.1
Architecture: amd64
CurrentDesktop: Unity
Date: Tue Jul 14 22:32:58 2015
InstallationDate: Installed on 2015-06-08 (36 days ago)
InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Release amd64 (20140417)
PackageArchitecture: all
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=de_DE.UTF-8
 SHELL=/bin/bash
SourcePackage: meld
UpgradeStatus: Upgraded to vivid on 2015-06-09 (35 days ago)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Jeffery Wilkins (djcanadianjeff)]

confirmed this bug exists on xenial xerus

meld version 3.14.2-1

meld crashed with AttributeError in on_fileentry_file_set(): 'NoneType' object has no attribute 'get_path'