Crashes on missing source file

[bjorn3]

Describe the bug

When a source file is missing gdbgui crashes with:

File not found: /checkout/src/libstd/rt.rs
The underlying gdb process has been killed. This tab will no longer function as expected.
Error occurred on server when running gdb command: gdb is not running

To Reproduce

1. load a binary compiled using rustc
2. press restart
3. step into a function of the rust std lib
4. crash

Expected behavior

Don't crash, but just handle it by showing for example the disassembly.

Screenshots
If applicable, add screenshots to help explain your problem.

Please complete the following information:

• OS: Linux laptopbjorn-lenovo 4.9.0-7-amd64 Dev/cs01/general improvements #1 SMP Debian 4.9.110-3+deb9u1 (2018-08-03) x86_64 GNU/Linux
• gdbgui version (gdbgui -v): 0.13.0.0
• gdb version (gdb -v): GNU gdb (Debian 7.12-6) 7.12.0.20161007-git
• browser [e.g. chrome, safari]: firefox
• python packages (pip freeze):
  blinker==1.3
  chardet==2.3.0
  click==6.6
  colorama==0.3.7
  cryptography==1.7.1
  cupshelpers==1.0
  decorator==4.0.11
  Flask==0.12.4
  Flask-Compress==1.4.0
  Flask-SocketIO==2.9.6
  gdbgui==0.13.0.0
  gevent==1.3.5
  greenlet==0.4.14
  httplib2==0.9.2
  idna==2.2
  itsdangerous==0.24
  Jinja2==2.8
  MarkupSafe==0.23
  networkx==1.11
  numpy==1.12.1
  pexpect==4.2.1
  Pillow==4.0.0
  ptyprocess==0.5.1
  pyasn1==0.1.9
  pycups==1.9.73
  pycurl==7.43.0
  pygdbmi==0.8.3.0
  Pygments==2.2.0
  pygobject==3.22.0
  pyinotify==0.9.6
  pyOpenSSL==16.2.0
  pysmbc==1.0.15.6
  python-apt==1.4.0b3
  python-debian==0.1.30
  python-debianbts==2.6.1
  python-engineio==2.2.0
  python-socketio==2.0.0
  PyYAML==3.12
  reportbug==7.1.7
  reportlab==3.3.0
  requests==2.12.4
  scipy==0.18.1
  simplejson==3.10.0
  six==1.10.0
  unattended-upgrades==0.1
  urllib3==1.19.1
  Werkzeug==0.11.15

[cs01]

This looks like a gdb issue. Perhaps try using the latest version of gdb, I know they have been making improvements regarding rust.

If the latest version of gdb still produces this issue, please reproduce it with the following setting turned on (click gear icon in gdbgui) and paste the commands gdbgui sent to gdb before the crash:

Print all sent commands in console, including those sent automatically by gdbgui