It was debug difficult of an error occurred by after handle pipeline

Code to reproduce the issue

It was difficult for us to debug error/exception, when an error/exception occurred by after handle pipeline.

These are situations that may occur.

Output has been emitted previously.
- When I have a config file and there is no declare(strict_types=1) and exists UTF8+BOM.
- Echo something in middleware or handler.
- etc..
Throw an errors/exceptions in ErrorHandler's listeners.
- When I attach a logger listener, and logging error.
- etc..

There will output an empty response (status 200). Then, we don't know what happened.

Expected results

Output messages by Whoops.

Actual results

Response OK (status code 200). And no error/exception outputed.

Suggestions

Remove $whoops->writeToOutput(false) in WhoopsFactory.

zend-expressive/src/Container/WhoopsFactory.php

Line 56 in 491da1e

$whoops->writeToOutput(false);

And add disable/enable send on both sides of get handleException result.

zend-expressive/src/Middleware/WhoopsErrorResponseGenerator.php

Lines 82 to 84 in 491da1e

    
           $response 
        
               ->getBody() 
        
               ->write($this->whoops->handleException($e));

        $sendOutput = $this->whoops->writeToOutput();
        $this->whoops->writeToOutput(false);
        $response
            ->getBody()
            ->write($this->whoops->handleException($e));
        $this->whoops->writeToOutput($sendOutput); //Restore to write to output.

@Moln would you be willing to create a pull request based on your suggestion?

@weierophinney Yeah, I created.

	$response
	->getBody()
	->write($this->whoops->handleException($e));