Catch throwables when evaluating state callbacks

src/wp-includes/interactivity-api/class-wp-interactivity-api.php

@@ -485,7 +485,21 @@ private function evaluate( $directive_value ) {
 		}
 
 		if ( $current instanceof Closure ) {
-			$current = $current();
+			try {
+				$current = $current();
+			} catch ( Throwable $e ) {
+				_doing_it_wrong(
+					__METHOD__,
+					sprintf(
+						/* translators: 1: Path pointing to an Interactivity API state property, 2: Namespace for an Interactivity API store. */
+						__( 'Uncaught error executing a derived state callback with path "%1$s" and namespace "%2$s".' ),
+						$path,
+						$ns
+					),
+					'6.6.0'
+				);
+				return null;
+			}
 		}
 
 		// Returns the opposite if it contains a negation operator (!).

tests/phpunit/tests/interactivity-api/wpInteractivityAPI.php

@@ -994,9 +994,9 @@ public function test_process_directives_does_not_change_inner_html_in_math() {
 	private function evaluate( $directive_value ) {
 		$generate_state = function ( $name ) {
 			return array(
-				'key'     => $name,
-				'nested'  => array( 'key' => $name . '-nested' ),
-				'derived' => function () {
+				'key'               => $name,
+				'nested'            => array( 'key' => $name . '-nested' ),
+				'derived'           => function () {
 					$state   = wp_interactivity_state();
 					$context = wp_interactivity_get_context();
 					return 'Derived state: ' .
@@ -1005,6 +1005,9 @@ private function evaluate( $directive_value ) {
 						'Derived context: ' .
 						$context['key'];
 				},
+				'derivedThatThrows' => function () {
+					throw new Error( 'Something bad happened.' );
+				},
 			);
 		};
 		$this->interactivity->state( 'myPlugin', $generate_state( 'myPlugin-state' ) );
@@ -1142,6 +1145,20 @@ public function test_evaluate_derived_state() {
 		$this->assertEquals( "Derived state: myPlugin-state\nDerived context: myPlugin-context", $result );
 	}
 
+
+	/**
+	 * Tests the `evaluate` method for derived state functions.
+	 *
+	 * @ticket 61037
+	 *
+	 * @covers ::evaluate
+	 * @expectedIncorrectUsage WP_Interactivity_API::evaluate
+	 */
+	public function test_evaluate_derived_state_that_throws() {
+		$result = $this->evaluate( 'state.derivedThatThrows' );
+		$this->assertEquals( null, $result );
+	}
+
 	/**
 	 * Tests the `kebab_to_camel_case` method.
 	 *