Unresolved error with validating logo for organization in JSON-LD markup: "A value for the 'url' field is required." - schema.org

Question

I'm trying to validate my JSON-LD markup, but Google's structured data tool is keep giving me error for Organization logo. I think it's a bug since it says I need to add URL.
https://example.com/ (A value for the url field is required.)
Google's tool: https://search.google.com/structured-data/testing-tool/u/0/
My script:
{
"#context":"http:\/\/schema.org",
"#type":"Article",
"name":"Test",
"image":"https:\/\/example.com\/favicon.ico",
"url":"https:\/\/example.com\/",
"author":{
"#type":"Person",
"name":"Admin"
},
"publisher":{
"#type":"Organization",
"name":"Orals",
"logo":"https:\/\/example.com\/favicon.ico"
},
"headline":"Welcome everyone!",
"datePublished":"2019-10-06",
"dateModified":"2019-10-06",
"articleBody":"Hi"
}
You can copy paste the above script into the tool's textarea.
I've been reading the official documentation and AFAIK I'm doing everything right. Here are a few related docs: Organization, logo

Answer 1

It’s a valid use of Schema.org. Google’s SDTT, however, is not a general Schema.org validator. The warnings and errors it reports are primarily about Google’s own search result features, which require the use of specific Schema.org terms in specific contexts.
For the AMP version of Google’s Article rich result, Google requires the publisher property, and the publisher’s logo has to have an ImageObject value instead of a URL value.
"publisher":{
"#type":"Organization",
"name":"Orals",
"logo": {
"#type": "ImageObject",
"url": "/logo.png"
}
},
If you don’t want this Article rich result in Google Search, or if you don’t use AMP, or if you can’t get it for other reasons (e.g., because you can’t provide all required properties), you can safely ignore this error in the SDTT.

Answer 2

I would only add the following information to the excellent answer of unor.
In the guide of Google for Logo has the following Google requirements for logo properties:
Images must be in .jpg, .png, or. gif format.
The format you specified for your logo is "logo":"https:\/\/example.com\/favicon.ico"
It can be assumed that Google ignores this format.