oEmbed: Fix PHP warnings when a registered provider is malformed

src/wp-includes/class-wp-oembed.php

@@ -273,7 +273,11 @@ public function get_provider( $url, $args = '' ) {
 		}
 
 		foreach ( $this->providers as $matchmask => $data ) {
-			list( $providerurl, $regex ) = $data;
+			if ( ! is_array( $data ) || ! isset( $data[0] ) ) {
+				continue;
+			}
+			$providerurl = $data[0];
+			$regex       = $data[1] ?? false;
 
 			// Turn the asterisk-type provider URLs into regex.
 			if ( ! $regex ) {

tests/phpunit/tests/oembed/wpOembed.php

@@ -276,4 +276,62 @@ public function test_wp_filter_pre_oembed_result_multisite_restores_state_if_no_
 		$this->assertFalse( $actual );
 		$this->assertSame( $current_blog_id, get_current_blog_id() );
 	}
+
+	/**
+	 * @ticket 65068
+	 *
+	 * @covers ::get_provider
+	 */
+	public function test_get_provider_skips_malformed_provider_entries() {
+		$warnings = array();
+
+		$error_handler = function ( $errno, $errstr ) use ( &$warnings ) {
+			if ( E_WARNING === $errno ) {
+				$warnings[] = $errstr;
+			}
+			return false;
+		};
+
+		set_error_handler( $error_handler );
+
+		$this->oembed->providers['bad_provider'] = array(
+			'url'      => '#https?://example\.site/.*#i',
+			'endpoint' => 'https://example.site/api/oembed',
+		);
+
+		$result = $this->oembed->get_provider( 'https://en.wikipedia.org/wiki/Rickrolling' );
+
+		restore_error_handler();
+
+		$this->assertFalse( $result );
+		$this->assertSame( array(), $warnings, 'PHP warnings were raised: ' . implode( ', ', $warnings ) );
+	}
+
+	/**
+	 * @ticket 65068
+	 *
+	 * @covers ::get_provider
+	 */
+	public function test_get_provider_handles_provider_without_regex_flag() {
+		$warnings = array();
+
+		$error_handler = function ( $errno, $errstr ) use ( &$warnings ) {
+			if ( E_WARNING === $errno ) {
+				$warnings[] = $errstr;
+			}
+			return false;
+		};
+
+		set_error_handler( $error_handler );
+
+		// Provider with only index 0 set (no regex flag) — should default $regex to false.
+		$this->oembed->providers['https://example.site/*'] = array( 'https://example.site/api/oembed' );
+
+		$result = $this->oembed->get_provider( 'https://example.site/video/123' );
+
+		restore_error_handler();
+
+		$this->assertSame( 'https://example.site/api/oembed', $result );
+		$this->assertSame( array(), $warnings, 'PHP warnings were raised: ' . implode( ', ', $warnings ) );
+	}
 }