Steps to Reproduce

1. load the file in KEIKAI-611
2. right-click column A, delete the column
3. repeat step 2 more than 3 times

Current Result

java.lang.NullPointerException
at io.keikai.ui.impl.MergeAggregation.newMergeAttributes (MergeAggregation.java:136)
at io.keikai.ui.impl.MergeAggregation.getMerge (MergeAggregation.java:114)
at io.keikai.ui.impl.MergeAggregation.getJSONObject (MergeAggregation.java:103)
at io.keikai.ui.impl.MergeAggregation.toJSONString (MergeAggregation.java:149)
at org.zkoss.json.JSONValue.toJSONString (JSONValue.java:97)
at org.zkoss.json.JSONObject.toJSONString (JSONObject.java:66)
at org.zkoss.json.JSONObject.toJSONString (JSONObject.java:45)
at org.zkoss.json.JSONObject.toJSONString (JSONObject.java:55)
at org.zkoss.json.JSONValue.toJSONString (JSONValue.java:97)
at org.zkoss.json.JSONArray.toJSONString (JSONArray.java:66)
at org.zkoss.json.JSONValue.toJSONString (JSONValue.java:107)
at org.zkoss.json.JSONArray.toJSONString (JSONArray.java:50)
at org.zkoss.json.JSONArray.toJSONString (JSONArray.java:187)
at org.zkoss.json.JSONValue.toJSONString (JSONValue.java:97)
at org.zkoss.json.JSONArray.toJSONString (JSONArray.java:50)
at org.zkoss.json.JSONArray.toJSONString (JSONArray.java:187)
at org.zkoss.json.JSONValue.toJSONString (JSONValue.java:97)
at org.zkoss.json.JSONArray.toJSONString (JSONArray.java:50)
at org.zkoss.json.JSONArray.toJSONString (JSONArray.java:187)
at org.zkoss.json.JSONValue.toJSONString (JSONValue.java:97)
at org.zkoss.json.JSONObject.toJSONString (JSONObject.java:66)
at org.zkoss.json.JSONObject.toJSONString (JSONObject.java:45)
at org.zkoss.json.JSONObject.toJSONString (JSONObject.java:55)
at org.zkoss.json.JSONObject.toString (JSONObject.java:75)
at org.zkoss.zk.au.http.HttpAuWriter.complete (HttpAuWriter.java:92)
at org.zkoss.zk.ui.impl.UiEngineImpl.execUpdate (UiEngineImpl.java:1356)
at org.zkoss.zk.au.http.DHtmlUpdateServlet.process (DHtmlUpdateServlet.java:571)
at org.zkoss.zk.au.http.DHtmlUpdateServlet.doGet (DHtmlUpdateServlet.java:451)
at org.zkoss.zk.au.http.DHtmlUpdateServlet.doPost (DHtmlUpdateServlet.java:459)

Expected Result

column delete without an error

Debug Information

• rect is null

Workaround