Merge pull request #80 from ConvertKit/fix-no-body-response

Check response in `get_error_message_string` is an array

src/class-convertkit-api-v4.php

@@ -1540,11 +1540,16 @@ private function is_production_site() {
 	 *
 	 * @since   2.0.0
 	 *
-	 * @param   array $response   API Response.
-	 * @return  string              Error Message(s).
+	 * @param   null|array $response   API Response.
+	 * @return  string                  Error Message(s).
 	 */
 	private function get_error_message_string( $response ) {
 
+		// If there is no API response body (such as a 429 error), there'll be no error message to return.
+		if ( ! is_array( $response ) ) {
+			return '';
+		}
+
 		// Most API responses contain the `errors` key.
 		if ( array_key_exists( 'errors', $response ) ) {
 			$error_message = '';

tests/wpunit/APITest.php

@@ -213,14 +213,7 @@ public function test429RateLimitHit()
 		// Force WordPress HTTP classes and functions to return a 429 error.
 		$this->mockResponses(
 			429,
-			'Rate limit hit',
-			wp_json_encode(
-				array(
-					'errors' => array(
-						'Rate limit hit.',
-					),
-				)
-			)
+			'Rate limit hit'
 		);
 		$result = $this->api->get_account(); // The API function we use doesn't matter, as mockResponse forces a 429 error.
 		$this->assertInstanceOf(WP_Error::class, $result);