Parse error with apparently valid JSON

[PSF1]

I have this JSON:

{
"query":"query {
	form.test-graphql {
		_id
		field_name
		field_date
		field_number
	}
","variables":{},"operationName":null}

That is validated and loaded by jsonviewer.

But, with JSONCompare I get this error:

Parse error on line 2: {"query":"query { form.test-
 ---------^ Expecting 'STRING', 'NUMBER', 'NULL', 'TRUE', 'FALSE', '{', '[', got 'undefined'

What could be the problem?

Thanks :)