MDL-59362 core: ensure we use 'new' when throwing exceptions

lib/classes/plugin_manager.php

@@ -146,7 +146,7 @@ class core_plugin_manager {
     public function get_plugin_types() {
         if (func_num_args() > 0) {
             if (!func_get_arg(0)) {
-                throw coding_exception('core_plugin_manager->get_plugin_types() does not support relative paths.');
+                throw new coding_exception('core_plugin_manager->get_plugin_types() does not support relative paths.');
             }
         }
         if ($this->plugintypes) {

lib/navigationlib.php

@@ -3651,7 +3651,7 @@ class breadcrumb_navigation_node extends navigation_node {
                  $this->$key = $value;
             }
         } else {
-            throw coding_exception('Not a valid breadcrumb_navigation_node');
+            throw new coding_exception('Not a valid breadcrumb_navigation_node');
         }
     }
 
@@ -3705,7 +3705,7 @@ class flat_navigation_node extends navigation_node {
                  $this->$key = $value;
             }
         } else {
-            throw coding_exception('Not a valid flat_navigation_node');
+            throw new coding_exception('Not a valid flat_navigation_node');
         }
         $this->indent = $indent;
     }