handle malformed json

Author: lsmith77

src/GettextPOGenerator.php

@@ -165,6 +165,9 @@ private function addStringsFromJsonFiles($translations) {
       // Load each JSON file to get source strings
       foreach ($this->JsonFiles() as $jsonFile) {
           $jsonTranslations = json_decode(file_get_contents($jsonFile), true);
+          if (!is_array($jsonTranslations)) {
+              throw new \Exception("The file '$jsonFile' is not valid JSON.'");
+          }
 
           foreach ($jsonTranslations as $key => $value) {
               $sourceStrings[] = $key;