Krikri::BecomeMethodError

A task whose become is enabled and whose ansible_become_method var renders to None/empty: real's become_loader refuses an empty plugin name (ValueError in PluginLoader.get_with_context), which the task books as the fatal "Task failed: A non-empty plugin name is required." - raised before any module runs (issue #395: adarnimrod.openbsd-bootstrap exports that var from vars/main.yml, so even the play's implicit Gathering Facts task dies on it). Subclasses UndefinedVariableError so every existing resolve_task_become rescue site books it as the task failure it is, unchanged.