diff --git a/src/ErrorHandler.php b/src/ErrorHandler.php
index a3c3f0b..91b80b0 100644
--- a/src/ErrorHandler.php
+++ b/src/ErrorHandler.php
@@ -7,6 +7,13 @@
 use Yii;
 
 /**
+ * ErrorHandler is an enhanced version of standard Yii error handler.
+ *
+ * Its main feature is conversion of the PHP errors into exceptions, so they may be processed via `try..catch` blocks.
+ *
+ * > Note: in order for error to exception conversion to work, the error handler component should be added to the
+ *   application "preload" section.
+ *
  * Application configuration example:
  *
  * ```
@@ -25,6 +32,9 @@
  * ]
  * ```
  *
+ * In addition, this class provides support for error/exception rendering as JSON output, which is useful for modern
+ * XHR and API implementation.
+ *
  * @author Paul Klimov <klimov.paul@gmail.com>
  * @since 1.0
  */
@@ -32,10 +42,25 @@ class ErrorHandler extends CErrorHandler
 {
     /**
      * @var bool whether to convert PHP Errors into Exceptions.
+     *
      * @see \ErrorException
      */
     public $convertErrorToException = true;
 
+    /**
+     * @var callable|null a PHP callback, which result should determine whether the error/exception should be displayed as JSON.
+     * The callback signature:
+     *
+     * ```
+     * function(): bool
+     * ```
+     *
+     * If not set default condition of matching  'Accept' HTTP request header will be used.
+     *
+     * @see shouldRenderErrorAsJson()
+     */
+    public $shouldRenderErrorAsJsonCallback;
+
     /**
      * {@inheritDoc}
      */
@@ -109,8 +134,21 @@ protected function setExceptionTrace(\Exception $exception, array $trace): void
         $traceReflection->setValue($exception, $trace);
     }
 
+    /**
+     * Checks if error/exception should be rendered as JSON.
+     *
+     * @see $shouldRenderErrorAsJsonCallback
+     *
+     * > Tip: you can invoke this method inside your custom handler specified via {@see $errorAction}.
+     *
+     * @return bool whether the error/exception should be rendered as JSON.
+     */
     public function shouldRenderErrorAsJson(): bool
     {
+        if ($this->shouldRenderErrorAsJsonCallback !== null) {
+            return call_user_func($this->shouldRenderErrorAsJsonCallback);
+        }
+
         return !empty($_SERVER['HTTP_ACCEPT']) && strcasecmp($_SERVER['HTTP_ACCEPT'], 'application/json') === 0;
     }
 
@@ -119,6 +157,8 @@ public function shouldRenderErrorAsJson(): bool
      * This method will display information from current {@see getError()} value.
      *
      * > Note: this method does NOT terminate the script.
+     *
+     * > Tip: you can invoke this method inside your custom handler specified via {@see $errorAction}.
      */
     public function renderErrorAsJson(): void
     {
@@ -154,10 +194,8 @@ public function renderErrorAsJson(): void
      */
     private function filterErrorTrace(array $trace): array
     {
-        /** @var ErrorTraceFilter $traceFilter */
-        $traceFilter = Yii::createComponent([
-            'class' => ErrorTraceFilter::class,
-        ]);
+        $traceFilter = new ErrorTraceFilter();
+        $traceFilter->maxTraceSize = $this->maxTraceSourceLines;
 
         return $traceFilter->filter($trace);
     }
@@ -169,12 +207,6 @@ protected function renderException(): void
     {
         $exception = $this->getException();
 
-        if ($this->errorAction !== null) {
-            Yii::app()->runController($this->errorAction);
-
-            return;
-        }
-
         if ($exception instanceof \CHttpException || !YII_DEBUG) {
             $this->renderError();
 
diff --git a/src/ErrorTraceFilter.php b/src/ErrorTraceFilter.php
index b1db0aa..5ecda84 100644
--- a/src/ErrorTraceFilter.php
+++ b/src/ErrorTraceFilter.php
@@ -5,6 +5,10 @@
 use CComponent;
 
 /**
+ * ErrorTraceFilter creates simplified representation of the stack trace.
+ *
+ * @see \yii1tech\error\handler\ErrorHandler::filterErrorTrace()
+ *
  * @author Paul Klimov <klimov.paul@gmail.com>
  * @since 1.0
  */
@@ -13,11 +17,17 @@ class ErrorTraceFilter extends CComponent
     /**
      * @var int maximum number of trace source code lines to be displayed. Defaults to 10.
      */
-    public $maxTraceSourceLines = 10;
+    public $maxTraceSize = 10;
 
+    /**
+     * Creates simplified representation of the given stack trace.
+     *
+     * @param array $trace raw trace.
+     * @return array simplified trace.
+     */
     public function filter(array $trace): array
     {
-        $trace = array_slice($trace, 0, $this->maxTraceSourceLines);
+        $trace = array_slice($trace, 0, $this->maxTraceSize);
 
         $result = [];
         foreach ($trace as $entry) {
@@ -81,9 +91,9 @@ private function simplifyArgument($value)
         } elseif (is_string($value)) {
             if (strlen($value) > 64) {
                 return "'" . substr($value, 0, 64) . "...'";
-            } else {
-                return "'" . $value . "'";
             }
+
+            return "'" . $value . "'";
         } elseif (is_array($value)) {
             return '[' . $this->simplifyArguments($value) . ']';
         } elseif ($value === null) {
diff --git a/tests/ErrorHandlerTest.php b/tests/ErrorHandlerTest.php
index 27f6e68..c82754f 100644
--- a/tests/ErrorHandlerTest.php
+++ b/tests/ErrorHandlerTest.php
@@ -2,8 +2,17 @@
 
 namespace yii1tech\error\handler\test;
 
+use Yii;
+
 class ErrorHandlerTest extends TestCase
 {
+    protected function tearDown(): void
+    {
+        unset($_SERVER['HTTP_ACCEPT']);
+
+        parent::tearDown();
+    }
+
     public function testCovertErrorToException(): void
     {
         try {
@@ -21,4 +30,28 @@ public function testCovertErrorToException(): void
         $this->assertSame('trigger_error', $trace[0]['function']);
         $this->assertFalse(empty($trace[0]['args']));
     }
+
+    public function testShouldRenderErrorAsJson(): void
+    {
+        $errorHandler = Yii::app()->getErrorHandler();
+
+        $_SERVER['HTTP_ACCEPT'] = 'application/json';
+        $this->assertTrue($errorHandler->shouldRenderErrorAsJson());
+
+        $_SERVER['HTTP_ACCEPT'] = 'text/html';
+        $this->assertFalse($errorHandler->shouldRenderErrorAsJson());
+
+        unset($_SERVER['HTTP_ACCEPT']);
+        $this->assertFalse($errorHandler->shouldRenderErrorAsJson());
+
+        $errorHandler->shouldRenderErrorAsJsonCallback = function() {
+            return true;
+        };
+        $this->assertTrue($errorHandler->shouldRenderErrorAsJson());
+
+        $errorHandler->shouldRenderErrorAsJsonCallback = function() {
+            return false;
+        };
+        $this->assertFalse($errorHandler->shouldRenderErrorAsJson());
+    }
 }
\ No newline at end of file
diff --git a/tests/ErrorTraceFilterTest.php b/tests/ErrorTraceFilterTest.php
new file mode 100644
index 0000000..3941e7e
--- /dev/null
+++ b/tests/ErrorTraceFilterTest.php
@@ -0,0 +1,95 @@
+<?php
+
+namespace yii1tech\error\handler\test;
+
+use yii1tech\error\handler\ErrorTraceFilter;
+
+class ErrorTraceFilterTest extends TestCase
+{
+    protected function prepareException($exceptionMessage = 'Test exception', $exceptionCode = 12345) : \Throwable
+    {
+        $args = [
+            'object' => new \stdClass(),
+            'bool' => true,
+            'string' => 'a string',
+            // Managed argument count being at 5, create a sub bucket
+            'sub' => [
+                'a_too_long_string' => str_repeat('a', 100),
+                'null' => null,
+                'resource' => tmpfile(),
+                'sub' => [
+                    'list' => ['foo', 'bar'],
+                    'list_with_holes' => [9 => 'nine', 5 => 'five'],
+                    'mixed_array' => ['foo', 'name' => 'bar']
+                ]
+            ],
+            'extra_param' => 'will not be normalized!'
+        ];
+
+        try {
+            // create a long stack trace
+            $closure = function ($exceptionMessage, $exceptionCode, array $allTypesOfArgs) {
+                throw new \RuntimeException($exceptionMessage, $exceptionCode);
+            };
+
+            call_user_func($closure, $exceptionMessage, $exceptionCode, $args);
+        } catch (\Throwable $exception) {
+            // shutdown test exception as prepared
+        }
+
+        return $exception;
+    }
+
+    public function testFilter(): void
+    {
+        $traceFilter = new ErrorTraceFilter();
+
+        $exceptionMessage = 'Test exception';
+        $exceptionCode = 12345;
+
+        $exception = $this->prepareException($exceptionMessage, $exceptionCode);
+
+        $trace = $traceFilter->filter($exception->getTrace());
+
+        $this->assertFalse(empty($trace[0]));
+    }
+
+    /**
+     * @depends testFilter
+     */
+    public function testShouldRestrictTraceSize(): void
+    {
+        $exception = $this->prepareException();
+
+        $traceFilter = new ErrorTraceFilter();
+        $traceFilter->maxTraceSize = 1;
+
+        $trace = $traceFilter->filter($exception->getTrace());
+
+        $this->assertCount($traceFilter->maxTraceSize, $trace);
+    }
+
+    /**
+     * @depends testShouldRestrictTraceSize
+     */
+    public function testShouldShowTraceArguments(): void
+    {
+        ini_set('zend.exception_ignore_args', 0); // Be sure arguments will be available on the stack trace
+        $exception = $this->prepareException();
+
+        $traceFilter = new ErrorTraceFilter();
+        $traceFilter->maxTraceSize = 1;
+
+        $trace = $traceFilter->filter($exception->getTrace());
+
+        $argsFound = false;
+        foreach ($trace as $entry) {
+            if (isset($entry['args'])) {
+                $argsFound = true;
+                break;
+            }
+        }
+
+        $this->assertTrue($argsFound);
+    }
+}
\ No newline at end of file