An error occurred: 'str' object has no attribute 'get'

# WHAT

**netplan try** crashes while processing yaml file. The same yaml was successfully tested (no errors) at Ubuntu 19.10.

# HOW TO REPRODUCE

```
user@pc:/# cat /etc/netplan/01-network-manager-all.yaml
# MANAGED BY ANSIBLE
network:
  version: 2

  ethernets:
    renderer: networkd
    eno2:
      optional: true
      addresses:
        - 192.168.5.15/24

  vlans:
    renderer: networkd
    vlan4:
      id: 4
      link: eno2
      optional: true
      addresses:
        - 192.168.4.15/24
      nameservers:
        addresses:
          - 8.8.8.8
          - 8.8.4.4

  wifis:
    renderer: NetworkManager

root@pc:/# netplan try

An error occurred: 'str' object has no attribute 'get'

Reverting.
Traceback (most recent call last):
  File "/usr/share/netplan/netplan/cli/commands/try_command.py", line 83, in command_try
    NetplanApply().command_apply(run_generate=True, sync=True, exit_on_error=False)
  File "/usr/share/netplan/netplan/cli/commands/apply.py", line 154, in command_apply
    NetplanApply.process_ovs_cleanup(config_manager, old_files_ovs, restart_ovs, exit_on_error)
  File "/usr/share/netplan/netplan/cli/commands/apply.py", line 324, in process_ovs_cleanup
    apply_ovs_cleanup(config_manager, ovs_old, ovs_current)
  File "/usr/share/netplan/netplan/cli/ovs.py", line 119, in apply_ovs_cleanup
    if (is_ovs_interface(i, config_manager.interfaces)):
  File "/usr/share/netplan/netplan/cli/ovs.py", line 102, in is_ovs_interface
    if interfaces[iface].get('openvswitch') is not None:
AttributeError: 'str' object has no attribute 'get'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/sbin/netplan", line 23, in <module>
    netplan.main()
  File "/usr/share/netplan/netplan/cli/core.py", line 50, in main
    self.run_command()
  File "/usr/share/netplan/netplan/cli/utils.py", line 211, in run_command
    self.func()
  File "/usr/share/netplan/netplan/cli/commands/try_command.py", line 66, in run
    self.run_command()
  File "/usr/share/netplan/netplan/cli/utils.py", line 211, in run_command
    self.func()
  File "/usr/share/netplan/netplan/cli/commands/try_command.py", line 94, in command_try
    self.revert()
  File "/usr/share/netplan/netplan/cli/commands/try_command.py", line 117, in revert
    NetplanApply().command_apply(run_generate=False, sync=True, exit_on_error=False)
  File "/usr/share/netplan/netplan/cli/commands/apply.py", line 154, in command_apply
    NetplanApply.process_ovs_cleanup(config_manager, old_files_ovs, restart_ovs, exit_on_error)
  File "/usr/share/netplan/netplan/cli/commands/apply.py", line 324, in process_ovs_cleanup
    apply_ovs_cleanup(config_manager, ovs_old, ovs_current)
  File "/usr/share/netplan/netplan/cli/ovs.py", line 119, in apply_ovs_cleanup
    if (is_ovs_interface(i, config_manager.interfaces)):
  File "/usr/share/netplan/netplan/cli/ovs.py", line 102, in is_ovs_interface
    if interfaces[iface].get('openvswitch') is not None:
AttributeError: 'str' object has no attribute 'get'
root@pc:/#

```

# SYSTEM INFO

```
Ubuntu 20.10
Linux kupc 5.8.0-29-generic #31-Ubuntu SMP Fri Nov 6 12:37:59 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux

libnetplan0/groovy,now 0.100-0ubuntu5 amd64 [installed,automatic]
netplan.io/groovy,now 0.100-0ubuntu5 amd64 [installed,automatic]
```