Add ignores to ErrorHandler

SpigotCore_Main/src/de/steamwar/core/ErrorHandler.java

@@ -73,6 +73,9 @@ public class ErrorHandler extends Handler {
         if(stacktrace.contains("POI data mismatch"))
             return;
 
+        if(message.isEmpty() && stacktrace.isEmpty())
+            return;
+
         try {
             SWException.log(message, stacktrace);
         } catch (SecurityException e) {
@@ -140,6 +143,7 @@ public class ErrorHandler extends Handler {
         startsWith.add("Biome with id");
         startsWith.add("1.16 and 1.16.1 clients are only partially supported");
         startsWith.add("Unable to parse CustomName from ");
+        startsWith.add("java.util.ConcurrentModificationException");
         ignoreStartsWith = Collections.unmodifiableList(startsWith);
 
         List<String> contains = new ArrayList<>();