made phpdoc types consistent with those defined in Hack

If the response contents has been sent before an error occurs, PHP
triggers the warning "Cannot modify header information - headers already sent"

This change ensure that the error message is echoed, while it's impossible
to change the HTTP status code and headers.

Debug.php

@@ -30,8 +30,8 @@ class Debug
      * If the Symfony ClassLoader component is available, a special
      * class loader is also registered.
      *
-     * @param integer $errorReportingLevel The level of error reporting you want
-     * @param Boolean $displayErrors       Whether to display errors (for development) or just log them (for production)
+     * @param int     $errorReportingLevel The level of error reporting you want
+     * @param bool    $displayErrors       Whether to display errors (for development) or just log them (for production)
      */
     public static function enable($errorReportingLevel = null, $displayErrors = true)
     {

ErrorHandler.php

@@ -56,8 +56,8 @@ class ErrorHandler
     /**
      * Registers the error handler.
      *
-     * @param integer $level The level at which the conversion to Exception is done (null to use the error_reporting() value and 0 to disable)
-     * @param Boolean $displayErrors Display errors (for dev environment) or just log they (production usage)
+     * @param int     $level The level at which the conversion to Exception is done (null to use the error_reporting() value and 0 to disable)
+     * @param bool    $displayErrors Display errors (for dev environment) or just log they (production usage)
      *
      * @return ErrorHandler The registered error handler
      */

ExceptionHandler.php

@@ -43,7 +43,7 @@ class ExceptionHandler
     /**
      * Registers the exception handler.
      *
-     * @param Boolean $debug
+     * @param bool    $debug
      *
      * @return ExceptionHandler The registered exception handler
      */
@@ -91,9 +91,11 @@ class ExceptionHandler
             $exception = FlattenException::create($exception);
         }
 
-        header(sprintf('HTTP/1.0 %s', $exception->getStatusCode()));
-        foreach ($exception->getHeaders() as $name => $value) {
-            header($name.': '.$value, false);
+        if (!headers_sent()) {
+            header(sprintf('HTTP/1.0 %s', $exception->getStatusCode()));
+            foreach ($exception->getHeaders() as $name => $value) {
+                header($name.': '.$value, false);
+            }
         }
 
         echo $this->decorate($this->getContent($exception), $this->getStylesheet($exception));

Tests/Exception/FlattenExceptionTest.php

@@ -113,7 +113,7 @@ class FlattenExceptionTest extends \PHPUnit_Framework_TestCase
 
         $this->assertEquals($exception->getMessage(), $flattened->getMessage(), 'The message is copied from the original exception.');
         $this->assertEquals($exception->getCode(), $flattened->getCode(), 'The code is copied from the original exception.');
-        $this->assertEquals(get_class($exception), $flattened->getClass(), 'The class is set to the class of the original exception');
+        $this->assertInstanceOf($flattened->getClass(), $exception, 'The class is set to the class of the original exception');
 
     }