Merge branch '3.4' into 4.0

* 3.4:
  Bump ext-mongodb to 1.5 on Travis
  Redesign the Debug error page in prod
  [DI] fix dumping deprecated service in yaml
  bumped Symfony version to 3.4.13
  updated VERSION for 3.4.12
  updated CHANGELOG for 3.4.12
  bumped Symfony version to 2.8.43
  updated VERSION for 2.8.42
  update CONTRIBUTORS for 2.8.42
  updated CHANGELOG for 2.8.42

Exception/ClassNotFoundException.php

@@ -26,6 +26,9 @@ class ClassNotFoundException extends FatalErrorException
             $previous->getSeverity(),
             $previous->getFile(),
             $previous->getLine(),
+            null,
+            true,
+            null,
             $previous->getPrevious()
         );
         $this->setTrace($previous->getTrace());

Exception/FatalErrorException.php

@@ -18,9 +18,9 @@ namespace Symfony\Component\Debug\Exception;
  */
 class FatalErrorException extends \ErrorException
 {
-    public function __construct(string $message, int $code, int $severity, string $filename, int $lineno, int $traceOffset = null, bool $traceArgs = true, array $trace = null)
+    public function __construct(string $message, int $code, int $severity, string $filename, int $lineno, int $traceOffset = null, bool $traceArgs = true, array $trace = null, \Throwable $previous = null)
     {
-        parent::__construct($message, $code, $severity, $filename, $lineno);
+        parent::__construct($message, $code, $severity, $filename, $lineno, $previous);
 
         if (null !== $trace) {
             if (!$traceArgs) {

Exception/UndefinedFunctionException.php

@@ -26,6 +26,9 @@ class UndefinedFunctionException extends FatalErrorException
             $previous->getSeverity(),
             $previous->getFile(),
             $previous->getLine(),
+            null,
+            true,
+            null,
             $previous->getPrevious()
         );
         $this->setTrace($previous->getTrace());

Exception/UndefinedMethodException.php

@@ -26,6 +26,9 @@ class UndefinedMethodException extends FatalErrorException
             $previous->getSeverity(),
             $previous->getFile(),
             $previous->getLine(),
+            null,
+            true,
+            null,
             $previous->getPrevious()
         );
         $this->setTrace($previous->getTrace());

ExceptionHandler.php

@@ -208,48 +208,54 @@ class ExceptionHandler
                 $title = 'Whoops, looks like something went wrong.';
         }
 
-        $content = '';
-        if ($this->debug) {
-            try {
-                $count = count($exception->getAllPrevious());
-                $total = $count + 1;
-                foreach ($exception->toArray() as $position => $e) {
-                    $ind = $count - $position + 1;
-                    $class = $this->formatClass($e['class']);
-                    $message = nl2br($this->escapeHtml($e['message']));
-                    $content .= sprintf(<<<'EOF'
-                        <div class="trace trace-as-html">
-                            <table class="trace-details">
-                                <thead class="trace-head"><tr><th>
-                                    <h3 class="trace-class">
-                                        <span class="text-muted">(%d/%d)</span>
-                                        <span class="exception_title">%s</span>
-                                    </h3>
-                                    <p class="break-long-words trace-message">%s</p>
-                                </th></tr></thead>
-                                <tbody>
-EOF
-                        , $ind, $total, $class, $message);
-                    foreach ($e['trace'] as $trace) {
-                        $content .= '<tr><td>';
-                        if ($trace['function']) {
-                            $content .= sprintf('at <span class="trace-class">%s</span><span class="trace-type">%s</span><span class="trace-method">%s</span>(<span class="trace-arguments">%s</span>)', $this->formatClass($trace['class']), $trace['type'], $trace['function'], $this->formatArgs($trace['args']));
-                        }
-                        if (isset($trace['file']) && isset($trace['line'])) {
-                            $content .= $this->formatPath($trace['file'], $trace['line']);
-                        }
-                        $content .= "</td></tr>\n";
-                    }
+        if (!$this->debug) {
+            return <<<EOF
+                <div class="container">
+                    <h1>$title</h1>
+                </div>
+EOF;
+        }
 
-                    $content .= "</tbody>\n</table>\n</div>\n";
-                }
-            } catch (\Exception $e) {
-                // something nasty happened and we cannot throw an exception anymore
-                if ($this->debug) {
-                    $title = sprintf('Exception thrown when handling an exception (%s: %s)', get_class($e), $this->escapeHtml($e->getMessage()));
-                } else {
-                    $title = 'Whoops, looks like something went wrong.';
+        $content = '';
+        try {
+            $count = count($exception->getAllPrevious());
+            $total = $count + 1;
+            foreach ($exception->toArray() as $position => $e) {
+                $ind = $count - $position + 1;
+                $class = $this->formatClass($e['class']);
+                $message = nl2br($this->escapeHtml($e['message']));
+                $content .= sprintf(<<<'EOF'
+                    <div class="trace trace-as-html">
+                        <table class="trace-details">
+                            <thead class="trace-head"><tr><th>
+                                <h3 class="trace-class">
+                                    <span class="text-muted">(%d/%d)</span>
+                                    <span class="exception_title">%s</span>
+                                </h3>
+                                <p class="break-long-words trace-message">%s</p>
+                            </th></tr></thead>
+                            <tbody>
+EOF
+                    , $ind, $total, $class, $message);
+                foreach ($e['trace'] as $trace) {
+                    $content .= '<tr><td>';
+                    if ($trace['function']) {
+                        $content .= sprintf('at <span class="trace-class">%s</span><span class="trace-type">%s</span><span class="trace-method">%s</span>(<span class="trace-arguments">%s</span>)', $this->formatClass($trace['class']), $trace['type'], $trace['function'], $this->formatArgs($trace['args']));
+                    }
+                    if (isset($trace['file']) && isset($trace['line'])) {
+                        $content .= $this->formatPath($trace['file'], $trace['line']);
+                    }
+                    $content .= "</td></tr>\n";
                 }
+
+                $content .= "</tbody>\n</table>\n</div>\n";
+            }
+        } catch (\Exception $e) {
+            // something nasty happened and we cannot throw an exception anymore
+            if ($this->debug) {
+                $title = sprintf('Exception thrown when handling an exception (%s: %s)', get_class($e), $this->escapeHtml($e->getMessage()));
+            } else {
+                $title = 'Whoops, looks like something went wrong.';
             }
         }
 
@@ -278,6 +284,14 @@ EOF;
      */
     public function getStylesheet(FlattenException $exception)
     {
+        if (!$this->debug) {
+            return <<<'EOF'
+                body { background-color: #fff; color: #222; font: 16px/1.5 -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif; margin: 0; }
+                .container { margin: 30px; max-width: 600px; }
+                h1 { color: #dc3545; font-size: 24px; }
+EOF;
+        }
+
         return <<<'EOF'
             body { background-color: #F9F9F9; color: #222; font: 14px/1.4 Helvetica, Arial, sans-serif; margin: 0; padding-bottom: 45px; }