AI: Catch Throwable in WP_AI_Client_Prompt_Builder so TypeErrors become WP_Error

[itzmekhokan]

WP_AI_Client_Prompt_Builder's contract is that any failure during a method chain puts the builder into an error state and is surfaced as a WP_Error from a generating method. The constructor and the __call() proxy enforce this with try/catch, but both only caught Exception.

__call() forwards caller arguments into the strict-typed php-ai-client SDK (usingTemperature(float), usingMaxTokens(int), etc. — the SDK uses strict_types=1). A wrong argument type throws a TypeError, which extends Error, not Exception. The existing catch missed it, so it escaped uncaught and fataled the request (HTTP 500) instead of returning a WP_Error.

Steps to reproduce

$builder = wp_ai_client_prompt( 'Write a haiku' );
// An array can never be coerced to float -> TypeError from usingTemperature().
$result = $builder->using_temperature( array( 0.7 ) )->generate_text();
// Expected: WP_Error. Before this change: uncaught TypeError -> fatal.

Changes

• Catch Throwable instead of Exception in the constructor and __call().
• Widen exception_to_wp_error() to accept Throwable. Its instanceof ladder already falls through to prompt_builder_error / 500 for unrecognized types, so Error/TypeError map cleanly with no other change.
• Add regression tests:
  • exception_to_wp_error() maps a TypeError to prompt_builder_error / 500.
  • End-to-end: passing an uncoercible argument type to a wrapped SDK method is caught and surfaced as a WP_Error from a generating method instead of fataling.

Testing instructions

Run the AI Client suite:

npm run test:php -- --group ai-client

181 tests, 463 assertions, all passing.

Trac ticket: https://core.trac.wordpress.org/ticket/65505

Use of AI Tools

AI assistance: Yes
Tool(s): Claude
Used for: Used for test cases. Reviewed and edited by me.

---

This Pull Request is for code review only. Please keep all other discussion in the Trac ticket. Do not merge this Pull Request. See GitHub Pull Requests for Code Review in the Core Handbook for more details.

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Props khokansardar, gziolo, alaminfirdows.

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[alaminfirdows]

To make it more readable and consistent, I prefer using $th instead of $e or $throwable. We already use $th in many other places, so it also keeps the naming consistent.

reference:

wordpress-develop/src/wp-includes/SimplePie/src/HTTP/Psr18Client.php

Line 152 in 2a5a37e

} catch (Throwable $th) {