fix npe on files with no content

CHANGELOG.md

@@ -15,6 +15,7 @@
 
 ### Fixed
 - Character unescaping for '.properties' files
+- Exception on json files without any content
 
 ## [2.0.0]
 ### BREAKING CHANGES

src/main/java/de/marhali/easyi18n/io/parser/json/JsonParserStrategy.java

@@ -36,9 +36,11 @@ public class JsonParserStrategy extends ParserStrategy {
 
         try(Reader reader = new InputStreamReader(vf.getInputStream(), vf.getCharset())) {
             JsonObject input = GSON.fromJson(reader, JsonObject.class);
+            if(input != null) { // @input is null if file is completely empty
                 JsonMapper.read(file.getLocale(), input, targetNode);
             }
         }
+    }
 
     @Override
     public void write(@NotNull TranslationData data, @NotNull TranslationFile file) throws IOException {