Fixed an issue with primitive type encryption

Author: jaaufauvre

src/Developer/Encryption/FieldLevelEncryption.php

@@ -93,7 +93,7 @@ private static function encryptPayloadPath($payloadJsonObject, $jsonPathIn, $jso
         }
 
         // Encrypt data at the given JSON path
-        $inJsonString = self::sanitizeJson(json_encode($inJsonObject));
+        $inJsonString = self::sanitizeJson(self::toJsonString($inJsonObject));
         $encryptedValueBytes = self::encryptBytes($params->getSecretKeyBytes(), $params->getIvBytes(), $inJsonString);
         $encryptedValue = EncodingUtils::encodeBytes($encryptedValueBytes, $config->getFieldValueEncoding());
 
@@ -261,6 +261,16 @@ private static function decryptBytes($key, $iv, $encryptedBytes) {
         return $bytes;
     }
 
+    private static function toJsonString($object) {
+        if (is_null($object)) {
+            throw new \InvalidArgumentException('Can\'t get a JSON string from a null object!');
+        }
+        if (!is_object($object) && !is_array($object)) {
+            return $object;
+        }
+        return json_encode($object);
+    }
+
     private static function sanitizeJson($json) {
         $json = str_replace("\n", '', $json);
         $json = str_replace("\r", '', $json);