Description

Namespaces can only contain alphanumeric characters, hyphens, underscores, and forward slashes, but as of today, we're not ensuring that namespaces have the correct format in all places that accept a namespace (directives, functions…) which could result in some confusion/bugs.

We should review all the code and ensure that an error message is displayed whenever a namespace is not correctly formatted.

In the runtime, to avoid increasing the bundle size, we could perform this check only in development (when the constant SCRIPT_DEBUG is true).

Reported by @gziolo in Slack.

Step-by-step reproduction instructions

1. Try to pass a namespace that does not comply with the format to the store() function in JavaScript or wp_interactivity_state() in PHP.
2. An error should be displayed.

Screenshots, screen recording, code snippet

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Environment info

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Please confirm that you have searched existing issues in the repo.

• Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

• Yes