Fix error - header already sent

Author: byjg

src/JwtSession.php

@@ -79,6 +79,10 @@ public function close()
      */
     public function destroy($session_id)
     {
+        if (headers_sent()) {
+            return false;
+        }
+
         setcookie(self::COOKIE_PREFIX . $this->suffix, null);
         return true;
     }
@@ -170,8 +174,11 @@ public function write($session_id, $session_data)
         $data = $jwt->createJwtData($this->unSerializeSessionData($session_data), $this->timeOutMinutes * 60);
         $token = $jwt->generateToken($data);
 
-        setcookie(self::COOKIE_PREFIX . $this->suffix, $token);
+        if (headers_sent()) {
+            return false;
+        }
 
+        setcookie(self::COOKIE_PREFIX . $this->suffix, $token);
         return true;
     }