Send Test Notification sends empty {{diff}}

[mvartuc]

Describe the bug
When I click "Send Test Notification" for my notification endpoint:
form://192.168.0.15:8000/process?:urls={{diff}}

I expect {{diff}} to contain something like the latest difference captured in the history, or something else... But it's completely empty. I get a notification error:

Failed to send Form POST notification: Bad Request - Unsupported Parameters., error=400.

testing with a telegram apprise url revealed that {{diff}} is completely empty on test notifications, which explains the above error.

Version
v0.50.8

How did you install?
Docker

To Reproduce

Steps to reproduce the behavior:

1. Go to Notifications for a watch
2. Add an apprise notification url (any one of them), include {{diff}} in the notification
3. Click "Send Test Notification"
4. Observe the empty {{diff}}

Always include an example URL!!!!!!!!!!!!
https://www.google.com (or any valid website on the internet that's accessible)

Expected behavior
"Send Test Notification" button sends a notification with the latest {{diff}} found.

Desktop (please complete the following information):

• OS: macOS Sequoia 15.5 arm64
• Browser: Arc Browser
• Version: 1.107.0 (66519)

[dgtlmoon]

#3159
and
#3162

[dgtlmoon]

@mvartuc can you confirm from which parts of the UI? from "settings" and also from "edit" of a watch?

[dgtlmoon]

solved in latest PR, I even added null:// notification type so we can see the whole round trip

[dgtlmoon]

Should be resolved in latest version, no feedback @mvartuc ?