Added exceptions hierarchy for backends exceptions not yet migrated classes to it.

Author: arabcoders

src/Libs/Exceptions/BackendException.php

@@ -0,0 +1,14 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Libs\Exceptions;
+
+use ErrorException;
+
+/**
+ * Base Exception class for the backends errors.
+ */
+class BackendException extends ErrorException
+{
+}

src/Libs/Exceptions/InvalidArgumentException.php

@@ -0,0 +1,14 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Libs\Exceptions;
+
+/**
+ * Class InvalidArgumentException
+ *
+ * This class represents an exception that is thrown by the backend logic.
+ */
+class InvalidArgumentException extends BackendException
+{
+}

src/Libs/BackendException.php renamed to src/Libs/Exceptions/RuntimeException.php

@@ -2,15 +2,13 @@
 
 declare(strict_types=1);
 
-namespace App\Libs;
-
-use ErrorException;
+namespace App\Libs\Exceptions;
 
 /**
- * Class BackendException
+ * Class RuntimeException
  *
  * This class represents an exception that is thrown by the backend logic.
  */
-class BackendException extends ErrorException
+class RuntimeException extends BackendException
 {
 }