Unquoted key doesn't show diagnostic error

[mchelen]

When editing this JSON the unquoted keys are highlighted red, but no errors or warnings appear in the diagnostic panel:

{
	hello: "world",
	foo: "bar"
}

Other JSON validators show errors like:

Error: Parse error on line 1:
{	hello: "world",	foo
--^
Expecting 'STRING', '}', got 'undefined'

or

Error:Strings should be wrapped in double quotes.[Code 17, Structure 2]
Error:Strings should be wrapped in double quotes.[Code 17, Structure 6]