If a `PluginExecutionContext().shutdown()` is called _before_ `PluginExecutionContext().start()` was called, this leads to an `AttributeError` exception since finalizer tries to access to attributes which were never defined.
If a `PluginExecutionContext().shutdown()` is called _before_ `PluginExecutionContext().start()` was called, this leads to an `AttributeError` exception since finalizer tries to access to attributes which were never defined.