Error: Invalid task name – grunt-contrib-watch spawn default change

Problem description

When running a Grunt project that uses grunt-contrib-watch, the default value of the spawn option changed from true in 0.4.x to false in 0.5.x. This shift can lead to unpredictable task execution order, especially when multiple watch targets modify each other’s source files. The resulting race conditions may surface as intermittent failures, sometimes reported as Invalid task name errors because spawned child processes are unable to register or complete their tasks before the parent process exits.

Constraints and uncertainty

The exact behavior depends on the Grunt core version, the plugin version, and the underlying file system’s event delivery semantics. Older documentation still shows the previous default, so developers may unintentionally rely on the old behavior. Additionally, the error surfaces only under certain timing conditions, making it hard to reproduce deterministically.

Specific questions

1. How can we reliably detect when the spawn default in grunt-contrib-watch is false for a given project?
2. What are the documented best‑practice patterns for coordinating multiple watch targets that modify shared files when spawn is false?
3. Is there a recommended configuration or plugin that mitigates the race condition introduced by the spawn default change without requiring a global upgrade?