Fix startup error that may happen when factions is shutdown improperly

src/main/java/com/massivecraft/factions/zcore/persist/json/JSONFPlayers.java

@@ -73,6 +73,7 @@ public class JSONFPlayers extends MemoryFPlayers {
         if (!this.file.exists()) return new HashMap<>();
         String content = DiscUtil.readCatch(this.file);
         if (content == null) return null;
+        try {
             Map<String, JSONFPlayer> data = this.gson.fromJson(content, new TypeToken<Map<String, JSONFPlayer>>() {
             }.getType());
             Set<String> list = new HashSet<>();
@@ -150,6 +151,14 @@ public class JSONFPlayers extends MemoryFPlayers {
             Bukkit.getLogger().log(Level.INFO, "Done converting players.json to UUID.");
         }
         return data;
+        } catch (NullPointerException exception) {
+            exception.printStackTrace();
+            if (this.file.length() < 200) {
+                return new HashMap<>();
+            } else {
+                throw exception;
+            }
+        }
     }
 
     private boolean doesKeyNeedMigration(String key) {