Proposed change

Tediore in Discord reported the following bug:

2020-02-22 21:44:37 ERROR (MainThread) [homeassistant.core] Error doing job: Task exception was never retrieved
Traceback (most recent call last):
  File "/usr/src/homeassistant/homeassistant/data_entry_flow.py", line 109, in async_init
    result = await self._async_handle_step(flow, flow.init_step, data)
  File "/usr/src/homeassistant/homeassistant/data_entry_flow.py", line 172, in _async_handle_step
    result: Dict = await getattr(flow, method)(user_input)
  File "/usr/src/homeassistant/homeassistant/components/vizio/config_flow.py", line 180, in async_step_import
    if entry.data[CONF_VOLUME_STEP] != import_config[CONF_VOLUME_STEP]:
KeyError: 'volume_step'

This is happening because volume_step is optional but the code assumes that it always exists. This change prevents that error from occurring by using get and providing a default volume_step when none is provided

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Checklist

• The code change is tested and works locally.
• Local tests pass. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
• I have followed the development checklist
• The code has been formatted using Black (black --fast homeassistant tests)
• Tests have been added to verify that the new code works.

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated for www.home-assistant.io

If the code communicates with devices, web services, or third-party tools:

• The manifest file has all fields filled out correctly.
  Updated and included derived files by running: python3 -m script.hassfest.
• New or updated dependencies have been added to requirements_all.txt.
  Updated by running python3 -m script.gen_requirements_all.
• Untested files have been added to .coveragerc.

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