Fix websocket search for related

[frenck]

Proposed change

Fixes

2021-04-01 20:26:24 ERROR (MainThread) [homeassistant.components.websocket_api.http.connection] [140600048560688] Error handling message: Unknown error
Traceback (most recent call last):
  File "/usr/src/homeassistant/homeassistant/components/websocket_api/decorators.py", line 18, in _handle_async_response
    await func(hass, connection, msg)
TypeError: object NoneType can't be used in 'await' expression

Introduced in #48499.

Alternatively, we could adjust the @websocket_api.async_response decorator to handle callbacks.

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

Additional information

• This PR fixes or closes issue: fixes "search/related" websocket api is throwing an execption #48602
• This PR is related to issue:
• Link to documentation pull request:

Checklist

• The code change is tested and works locally.
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[probot-home-assistant]

Hey there @home-assistant/core, mind taking a look at this pull request as its been labeled with an integration (search) you are listed as a codeowner for? Thanks!
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