Fix webhook exception when empty json data is sent

[mikedast]

Proposed change

As describe in #148298, Dahua cameras web hook implementation, send a GET request, and set the "Content-Type" header to application/json, without providing any payload. This will result in an exception in "homeassistant/components/webhook/init.py":

2025-07-06 17:17:35.106 ERROR (MainThread) [homeassistant.components.webhook] Error processing webhook ivs-patio-5daAWNr1Q1ZSGRcBIcnK7BJ2
Traceback (most recent call last):
  File "/usr/src/homeassistant/homeassistant/components/webhook/__init__.py", line 194, in async_handle_webhook
    response: Response | None = await webhook["handler"](hass, webhook_id, request)
                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/src/homeassistant/homeassistant/components/webhook/trigger.py", line 64, in _handle_webhook
    base_result["json"] = await request.json()
                          ^^^^^^^^^^^^^^^^^^^^
  File "/usr/src/homeassistant/homeassistant/components/http/__init__.py", line 310, in json
    return json_loads(await self.read())
  File "/usr/src/homeassistant/homeassistant/util/json.py", line 42, in json_loads
    return orjson.loads(obj)  # type:ignore[no-any-return]
           ~~~~~~~~~~~~^^^^^
orjson.JSONDecodeError: Input is a zero-length, empty document: line 1 column 1 (char 0)

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)
• Deprecation (breaking change to happen in the future)
• 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: fix Webhook trigger fails when http GET call do not include any payload #148298
• This PR is related to issue: Webhook trigger fails when http GET call do not include any payload #148298
• Link to documentation pull request:
• Link to developer documentation pull request:
• Link to frontend pull request:

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[home-assistant]

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

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[mikedast]

Sorry I run into commit authoring issues with previous PR, decided to create a new branch.

[MartinHjelmare]

Please stop merging the dev branch into your feature branch. We can't merge the PR until we see that CI passes. Whenever you update the branch we need to run CI again.

We only need to merge dev branch into the feature branch if there's a merge conflict or if we know we need something from dev.

[MartinHjelmare]

Thanks!