TypeError: can only concatenate list (not "str") to list

[imp1sh]

I made a backup of two different systems (Archer C7 v2 and X86_64 Qemu guest).
Both I tried to reverse with the following lines:

from netjsonconfig import OpenWrt
#router = OpenWrt(native=open('./backup-g0.sim.libcom.de-2018-10-10.tar.gz'))
router = OpenWrt(native=open('./backup-OpenWrt-2018-10-10.tar.gz'))
print(router.render)

In both cases this results in the following error:
python reverse.py

Traceback (most recent call last):
  File "reverse.py", line 3, in <module>
    router = OpenWrt(native=open('./backup-OpenWrt-2018-10-10.tar.gz'))
  File "/usr/lib/python2.7/site-packages/netjsonconfig/backends/base/backend.py", line 47, in __init__
    self.parse(native)
  File "/usr/lib/python2.7/site-packages/netjsonconfig/backends/base/backend.py", line 280, in parse
    self.to_netjson()
  File "/usr/lib/python2.7/site-packages/netjsonconfig/backends/base/backend.py", line 293, in to_netjson
    value = converter.to_netjson()
  File "/usr/lib/python2.7/site-packages/netjsonconfig/backends/base/converter.py", line 108, in to_netjson
    result = self.to_netjson_loop(block, result, index + 1)
  File "/usr/lib/python2.7/site-packages/netjsonconfig/backends/openwrt/converters/interfaces.py", line 206, in to_netjson_loop
    interface = self.__netjson_interface(block)
  File "/usr/lib/python2.7/site-packages/netjsonconfig/backends/openwrt/converters/interfaces.py", line 217, in __netjson_interface
    interface = self.__netjson_addresses(interface)
  File "/usr/lib/python2.7/site-packages/netjsonconfig/backends/openwrt/converters/interfaces.py", line 262, in __netjson_addresses
    for address in ipv4 + ipv6:
TypeError: can only concatenate list (not "str") to list

new.tar.gz

[nemesifier]

This is somewhat related to #104, the backward conversion process needs to be improved.
I'm adding these two tasks to the task list for the Google Code-In program.

[nemesifier]

@imp1sh, @anonguy is doing great work to fix the issue you reported in #119. Thanks again for your report. I hope we'll get it fixed very soon.

[nemesifier]

(actually his patch should already work, only some minor corrections are missing)

[yasharora102]

If no one is working on this I have taken this task under GCI. Also, It would be great to get the current position of the bug. 🙂