Generators are not supported for JSON responses.

[weierophinney]

Code to reproduce the issue

function getSomeData(): Generator {
    yield 1 => 'One';
    yield 2 => 'Two';
    yield 3 => 'Three';
}

$data = getSomeData();
$json = new Zend\Diactoros\Response\JsonResponse($data);

Expected results

Response should consume the generator and treat it as if a normal PHP array was passed in:

$data = [
    1 => 'One',
    2 => 'Two',
    3 => 'Three'
];

$json = new Zend\Diactoros\Response\JsonResponse($data);

Actual results

An error is thrown instead: "Trying to clone an uncloneable object of class Generator..."

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Originally posted by @nbish11 at zendframework/zend-diactoros#365

[Xerkus]

JsonResponse expectation for $data is array or value bag object such as stdclass, same as values passed to json_encode().

phpdoc and documentation needs an update to clarify this expectation.