Fix static code analysis issues

Author: pgrigoruta

src/Api/BaseClient.php

@@ -138,7 +138,7 @@ private function logMessage(Message $message)
     /**
      * Parse the body of a JSON response.
      */
-    private function parseResponse(ResponseInterface $response = null): array
+    private function parseResponse(ResponseInterface $response = null)
     {
         $body = $response
             ? (string) $response->getBody()

src/Api/Exception.php

@@ -106,7 +106,7 @@ private static function createExceptionMessage(
 
         try {
             $result = guzzle_json_decode((string) $response->getBody(), true);
-            if (isset($result['message'])) {
+            if (\is_array($result) && isset($result['message'])) {
                 return $result['message'];
             }
         } catch (\InvalidArgumentException $e) {

src/Api/Message.php

@@ -81,7 +81,7 @@ public static function createFromString(string $json): self
     {
         $data = guzzle_json_decode($json, true);
 
-        if (
+        if (!\is_array($data) ||
             !isset($data['api']) ||
             !isset($data['request']) ||
             !isset($data['response']) ||

src/Api/Requester.php

@@ -82,13 +82,11 @@ private function createCustomException(ClientException $exception): Exception
     {
         $errorId = '';
         $response = $exception->getResponse();
-        if ($response) {
-            try {
-                $data = guzzle_json_decode((string) $response->getBody(), true);
-                $errorId = (string) $data['sys']['id'] ?? '';
-            } catch (InvalidArgumentException $invalidArgumentException) {
-                $errorId = 'InvalidResponseBody';
-            }
+        try {
+            $data = guzzle_json_decode((string) $response->getBody(), true);
+            $errorId = (\is_array($data) && (string) $data['sys']['id']) ? $data['sys']['id'] : '';
+        } catch (InvalidArgumentException $invalidArgumentException) {
+            $errorId = 'InvalidResponseBody';
         }
 
         $exceptionClass = $this->getExceptionClass($errorId);