Block Supports: Guard against non-string attribute values to avoid fatal errors (Backport for GB #80501)

[im3dabasia]

Trac ticket: https://core.trac.wordpress.org/ticket/65774

What?

Backport PR of WordPress/gutenberg#80494

Guards block supports callbacks against non-string (and other wrong-typed) attribute values so they no longer cause fatalTypeErrors on the front end. (Block support is handled in a this PR.)

Why?

block.json / theme.json types aren't enforced at render time, so wrong-typed values from hand-editing, imports, or AI-generated content reach strict PHP ops (explode, preg_match, str_contains, addcslashes, parse_url, array_column, wp_strip_all_tags, array offsets) and fatal in PHP 8+.

How?

Following the existing idiom guard with is_string() / is_array() / is_scalar() before each strict op and treat a wrong-typed value as absent.

Testing Instructions

Existing tests should pass

Testing Instructions for Keyboard

N/A — no UI changes.

Use of AI Tools

Claude Code

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[ramonjd]

Faithful backport. Nothing to fix in the code. Just needs a track ticket + ticket number in the tests.

Thanks for getting to this!

I reckon it's okay to target the 7.2 milestone for this, what you do think?

[im3dabasia]

Thanks for the review!

I reckon it's okay to target the 7.2 milestone for this, what you do think?

Yes, this should be fine.

If you have a moment, would you mind creating the Trac ticket for this issue? I'm not sure why, but I don't seem to have the Create Ticket button on my Trac screen. Reference

[ramonjd]

Here it is!

https://core.trac.wordpress.org/ticket/65774

[im3dabasia]

Thanks @ramonjd for the continued efforts to move this PR forward.

I've updated the tests to include the Core ticket. I think this is in good shape for us to ship in WordPress 7.2.