diff --git a/README.md b/README.md
index 05cd234..2bf515c 100644
--- a/README.md
+++ b/README.md
@@ -199,5 +199,7 @@ Hello <?= html($name) ?>
 
 ## Exceptions
 
-* `\RuntimeException` - If template does not exist
+* `\Slim\Views\Exception\PhpTemplateNotFoundException` - If template layout does not exist
+* `\Slim\Views\Exception\PhpTemplateNotFoundException` - If template does not exist
+* `\RuntimeException` - If the template output could not be fetched
 * `\InvalidArgumentException` - If $data contains 'template'
diff --git a/phpstan.neon b/phpstan.neon
index b35f3d4..7f33c04 100644
--- a/phpstan.neon
+++ b/phpstan.neon
@@ -1,5 +1,5 @@
 parameters:
-	level: 5
+	level: 8
 	paths:
 		- src
 		- tests
diff --git a/src/PhpRenderer.php b/src/PhpRenderer.php
index ffec787..a73ac25 100644
--- a/src/PhpRenderer.php
+++ b/src/PhpRenderer.php
@@ -12,6 +12,7 @@
 
 use InvalidArgumentException;
 use Psr\Http\Message\ResponseInterface;
+use RuntimeException;
 use Slim\Views\Exception\PhpTemplateNotFoundException;
 use Throwable;
 
@@ -19,13 +20,16 @@ class PhpRenderer
 {
     protected string $templatePath;
 
+    /**
+     * @var array<string, mixed>
+     */
     protected array $attributes;
 
     protected string $layout;
 
     /**
      * @param string $templatePath
-     * @param array  $attributes
+     * @param array<string, mixed> $attributes
      * @param string $layout
      */
     public function __construct(string $templatePath = '', array $attributes = [], string $layout = '')
@@ -37,12 +41,12 @@ public function __construct(string $templatePath = '', array $attributes = [], s
 
     /**
      * @param ResponseInterface $response
-     * @param string            $template
-     * @param array             $data
-     *
-     * @return ResponseInterface
+     * @param string $template
+     * @param array<string, mixed> $data
      *
      * @throws Throwable
+     *
+     * @return ResponseInterface
      */
     public function render(ResponseInterface $response, string $template, array $data = []): ResponseInterface
     {
@@ -59,16 +63,12 @@ public function getLayout(): string
         return $this->layout;
     }
 
-    /**
-     * @param string $layout
-     */
-
     /**
      * @param string $layout
      *
-     * @return void
-     *
      * @throws PhpTemplateNotFoundException
+     *
+     * @return void
      */
     public function setLayout(string $layout): void
     {
@@ -80,7 +80,7 @@ public function setLayout(string $layout): void
     }
 
     /**
-     * @return array
+     * @return array<string, mixed>
      */
     public function getAttributes(): array
     {
@@ -88,7 +88,7 @@ public function getAttributes(): array
     }
 
     /**
-     * @param array $attributes
+     * @param array<string, mixed> $attributes
      *
      * @return void
      */
@@ -99,7 +99,7 @@ public function setAttributes(array $attributes): void
 
     /**
      * @param string $key
-     * @param        $value
+     * @param mixed $value
      *
      * @return void
      */
@@ -140,12 +140,12 @@ public function setTemplatePath(string $templatePath): void
 
     /**
      * @param string $template
-     * @param array  $data
-     * @param bool   $useLayout
-     *
-     * @return string
+     * @param array<string, mixed> $data
+     * @param bool $useLayout
      *
      * @throws Throwable
+     *
+     * @return string
      */
     public function fetch(string $template, array $data = [], bool $useLayout = false): string
     {
@@ -160,11 +160,11 @@ public function fetch(string $template, array $data = [], bool $useLayout = fals
 
     /**
      * @param string $template
-     * @param array  $data
-     *
-     * @return string
+     * @param array<string, mixed> $data
      *
      * @throws Throwable
+     *
+     * @return string
      */
     public function fetchTemplate(string $template, array $data = []): string
     {
@@ -173,8 +173,9 @@ public function fetchTemplate(string $template, array $data = []): string
         }
 
         if (!$this->templateExists($template)) {
-            throw new PhpTemplateNotFoundException('View cannot render "' . $template
-                                                   . '" because the template does not exist');
+            throw new PhpTemplateNotFoundException(
+                'View cannot render "' . $template . '" because the template does not exist'
+            );
         }
 
         $data = array_merge($this->attributes, $data);
@@ -182,6 +183,9 @@ public function fetchTemplate(string $template, array $data = []): string
             ob_start();
             $this->protectedIncludeScope($this->templatePath . $template, $data);
             $output = ob_get_clean();
+            if ($output === false) {
+                throw new RuntimeException('Failed to fetch the template output');
+            }
         } catch (Throwable $e) {
             ob_end_clean();
             throw $e;
@@ -205,7 +209,7 @@ public function templateExists(string $template): bool
 
     /**
      * @param string $template
-     * @param array  $data
+     * @param array<string, mixed> $data
      *
      * @return void
      */
diff --git a/tests/PhpRendererTest.php b/tests/PhpRendererTest.php
index b3e68bd..0e2284e 100644
--- a/tests/PhpRendererTest.php
+++ b/tests/PhpRendererTest.php
@@ -18,6 +18,7 @@
 use Slim\Views\Exception\PhpTemplateNotFoundException;
 use Slim\Views\PhpRenderer;
 use Throwable;
+use UnexpectedValueException;
 
 class PhpRendererTest extends TestCase
 {
@@ -25,7 +26,7 @@ public function testRenderer(): void
     {
         $renderer = new PhpRenderer(__DIR__ . '/_files/');
         $headers = new Headers();
-        $body = new Stream(fopen('php://temp', 'r+'));
+        $body = $this->createStream();
         $response = new Response(200, $headers, $body);
         $newResponse = $renderer->render($response, 'template.phtml', ['hello' => 'Hi']);
         $newResponse->getBody()->rewind();
@@ -36,7 +37,7 @@ public function testRenderConstructor(): void
     {
         $renderer = new PhpRenderer(__DIR__ . '/_files');
         $headers = new Headers();
-        $body = new Stream(fopen('php://temp', 'r+'));
+        $body = $this->createStream();
         $response = new Response(200, $headers, $body);
         $newResponse = $renderer->render($response, 'template.phtml', ['hello' => 'Hi']);
         $newResponse->getBody()->rewind();
@@ -45,12 +46,11 @@ public function testRenderConstructor(): void
 
     public function testAttributeMerging(): void
     {
-
         $renderer = new PhpRenderer(__DIR__ . '/_files/', [
             'hello' => 'Hello'
         ]);
         $headers = new Headers();
-        $body = new Stream(fopen('php://temp', 'r+'));
+        $body = $this->createStream();
         $response = new Response(200, $headers, $body);
         $newResponse = $renderer->render($response, 'template.phtml', [
             'hello' => 'Hi'
@@ -63,12 +63,12 @@ public function testExceptionInTemplate(): void
     {
         $renderer = new PhpRenderer(__DIR__ . '/_files/');
         $headers = new Headers();
-        $body = new Stream(fopen('php://temp', 'r+'));
+        $body = $this->createStream();
         $response = new Response(200, $headers, $body);
         try {
             $newResponse = $renderer->render($response, 'exception_layout.phtml');
         } catch (Throwable $t) {
-        // Simulates an error template
+            // Simulates an error template
             $newResponse = $renderer->render($response, 'template.phtml', [
                 'hello' => 'Hi'
             ]);
@@ -82,7 +82,7 @@ public function testExceptionForTemplateInData(): void
     {
         $renderer = new PhpRenderer(__DIR__ . '/_files/');
         $headers = new Headers();
-        $body = new Stream(fopen('php://temp', 'r+'));
+        $body = $this->createStream();
         $response = new Response(200, $headers, $body);
         $this->expectException(InvalidArgumentException::class);
         $renderer->render($response, 'template.phtml', [
@@ -94,7 +94,7 @@ public function testTemplateNotFound(): void
     {
         $renderer = new PhpRenderer(__DIR__ . '/_files/');
         $headers = new Headers();
-        $body = new Stream(fopen('php://temp', 'r+'));
+        $body = $this->createStream();
         $response = new Response(200, $headers, $body);
         $this->expectException(PhpTemplateNotFoundException::class);
         $renderer->render($response, 'adfadftemplate.phtml', []);
@@ -105,24 +105,30 @@ public function testLayout(): void
         $renderer = new PhpRenderer(__DIR__ . '/_files/', ['title' => 'My App']);
         $renderer->setLayout('layout.phtml');
         $headers = new Headers();
-        $body = new Stream(fopen('php://temp', 'r+'));
+        $body = $this->createStream();
         $response = new Response(200, $headers, $body);
         $newResponse = $renderer->render($response, 'template.phtml', ['title' => 'Hello - My App', 'hello' => 'Hi']);
         $newResponse->getBody()->rewind();
-        $this->assertEquals('<html><head><title>Hello - My App</title></head><body>Hi<footer>This is the footer'
-                            . '</footer></body></html>', $newResponse->getBody()->getContents());
+        $this->assertEquals(
+            '<html><head><title>Hello - My App</title></head><body>Hi<footer>This is the footer'
+            . '</footer></body></html>',
+            $newResponse->getBody()->getContents()
+        );
     }
 
     public function testLayoutConstructor(): void
     {
         $renderer = new PhpRenderer(__DIR__ . '/_files', ['title' => 'My App'], 'layout.phtml');
         $headers = new Headers();
-        $body = new Stream(fopen('php://temp', 'r+'));
+        $body = $this->createStream();
         $response = new Response(200, $headers, $body);
         $newResponse = $renderer->render($response, 'template.phtml', ['title' => 'Hello - My App', 'hello' => 'Hi']);
         $newResponse->getBody()->rewind();
-        $this->assertEquals('<html><head><title>Hello - My App</title></head><body>Hi<footer>This is the footer'
-                            . '</footer></body></html>', $newResponse->getBody()->getContents());
+        $this->assertEquals(
+            '<html><head><title>Hello - My App</title></head><body>Hi<footer>This is the footer'
+            . '</footer></body></html>',
+            $newResponse->getBody()->getContents()
+        );
     }
 
     public function testExceptionInLayout(): void
@@ -130,12 +136,12 @@ public function testExceptionInLayout(): void
         $renderer = new PhpRenderer(__DIR__ . '/_files/');
         $renderer->setLayout('exception_layout.phtml');
         $headers = new Headers();
-        $body = new Stream(fopen('php://temp', 'r+'));
+        $body = $this->createStream();
         $response = new Response(200, $headers, $body);
         try {
             $newResponse = $renderer->render($response, 'template.phtml');
         } catch (Throwable $t) {
-        // PHP 7+
+            // PHP 7+
             // Simulates an error template
             $renderer->setLayout('');
             $newResponse = $renderer->render($response, 'template.phtml', [
@@ -159,7 +165,7 @@ public function testContentDataKeyShouldBeIgnored(): void
         $renderer = new PhpRenderer(__DIR__ . '/_files/');
         $renderer->setLayout('layout.phtml');
         $headers = new Headers();
-        $body = new Stream(fopen('php://temp', 'r+'));
+        $body = $this->createStream();
         $response = new Response(200, $headers, $body);
         $newResponse = $renderer->render(
             $response,
@@ -167,14 +173,27 @@ public function testContentDataKeyShouldBeIgnored(): void
             ['title' => 'Hello - My App', 'hello' => 'Hi', 'content' => 'Ho']
         );
         $newResponse->getBody()->rewind();
-        $this->assertEquals('<html><head><title>Hello - My App</title></head><body>Hi<footer>This is the footer'
-                            . '</footer></body></html>', $newResponse->getBody()->getContents());
+        $this->assertEquals(
+            '<html><head><title>Hello - My App</title></head><body>Hi<footer>This is the footer'
+            . '</footer></body></html>',
+            $newResponse->getBody()->getContents()
+        );
     }
 
-    public function testTemplateExists()
+    public function testTemplateExists(): void
     {
         $renderer = new PhpRenderer(__DIR__ . '/_files/');
         $this->assertTrue($renderer->templateExists('layout.phtml'));
         $this->assertFalse($renderer->templateExists('non-existant-template'));
     }
+
+    private function createStream(): Stream
+    {
+        $resource = fopen('php://temp', 'r+');
+        if ($resource === false) {
+            throw new UnexpectedValueException();
+        }
+
+        return new Stream($resource);
+    }
 }