Fix preferences load bug

src/preferences/preferences.cpp

@@ -102,8 +102,10 @@ namespace preferences {
 
         // Open the file and read it into a buffer
         if (!msc::open(PREFERENCES_PATH), false) return;
-        msc::read(buffer, JSON_SIZE);
+        size_t read = msc::read(buffer, JSON_SIZE);
         msc::close();
+        
+        buffer[read] = '\0';
 
         // Deserialize the JSON document
         DeserializationError error = deserializeJson(config_doc, buffer);