Add input validation for $data parameter in wp_add_inline_script()

[parinpanjari]

Problem: The wp_add_inline_style() function in wp-includes/functions.wp-styles.php lacks validation for the $data parameter, expected to be a non-empty string containing CSS. Invalid input (e.g., null, array, or empty string) could cause PHP notices or unexpected behavior in WP_Styles::add_inline_style().

Proposed Fix: Add a type and emptiness check with _doing_it_wrong() notice and return false on failure.

Reasoning:

• Prevents errors from invalid input.
• Aligns with WordPress API validation practices.
• Backward-compatible, only affects invalid calls.

[swissspidy]

It's really up to the developer to provide the correct data type. Can't be hard to provide a non-empty string. If they do something wrong, they deserve to get a warning. So IMHO we shouldn't add this.

[knutsp]

WordPress should not prevent PHP errors/warnings from developers.

"Doing it wrong" is for common misconceptions or bad practices, or when the best working/correct way of doing things has changed, things that can not be catched by a simple PHP error or warning.