Added base exception

Author: WalterWoshid

composer.json

@@ -1,7 +1,7 @@
 {
     "name": "okapi/singleton",
     "description": "PHP Singleton is a PHP library that allows you to create singleton classes with a trait.",
-    "version": "1.0.2",
+    "version": "1.0.3",
     "type": "library",
     "homepage": "https://github.com/okapi-web/php-singleton",
     "license": "MIT",

src/Exceptions/AlreadyInitializedException.php

@@ -2,14 +2,12 @@
 
 namespace Okapi\Singleton\Exceptions;
 
-use RuntimeException;
-
 /**
  * # Already Initialized Exception
  *
  * This exception is thrown when a singleton instance is already initialized.
  */
-class AlreadyInitializedException extends RuntimeException
+class AlreadyInitializedException extends SingletonException
 {
     /**
      * AlreadyInitializedException constructor.

src/Exceptions/NotInitializedException.php

@@ -2,14 +2,12 @@
 
 namespace Okapi\Singleton\Exceptions;
 
-use RuntimeException;
-
 /**
  * # Not Initialized Exception
  *
  * This exception is thrown when a singleton is not initialized.
  */
-class NotInitializedException extends RuntimeException
+class NotInitializedException extends SingletonException
 {
     /**
      * NotInitializedException constructor.

src/Exceptions/SingletonException.php

@@ -0,0 +1,14 @@
+<?php
+
+namespace Okapi\Singleton\Exceptions;
+
+use RuntimeException;
+
+/**
+ * # Singleton exception
+ *
+ * Base class for all singleton exceptions.
+ */
+abstract class SingletonException extends RuntimeException
+{
+}