Add Msf::ModuleLoadError exception

lib/msf/core/exceptions.rb

@@ -48,10 +48,22 @@ class ValidationError < ArgumentError
   end
 end
 
+
 ###
 #
-# This exception is raised when the module cache is invalidated.  It is
-# handled internally by the ModuleManager.
+# This exception is raised when a module fails to load.
+#
+# It is used by Msf::Modules::Loader::Base.
+#
+###
+class ModuleLoadError < RuntimeError
+end
+
+###
+#
+# This exception is raised when the module cache is invalidated.
+#
+# It is handled internally by the ModuleManager.
 #
 ###
 class ModuleCacheInvalidated < RuntimeError