Improve RowHistoryData.setHistoryData.

static/plugin_event/src/grid/RowHistoryData.js

@@ -158,11 +158,22 @@ Ext.define("Event.grid.RowHistoryData", {
     setHistoryData: function (value) {
 
         "use strict";
-        var me = this,
-            events = me.eventStore,
-            idEvent= me.historyId_events,
-            cfg = Event.getHistoryDataConfig(events, idEvent);
+        var me= this,
+            events, idEvent, cfg;
+
+        if (me.readOnly) {
+            me.setSource(value);
+
+        } else {
+            events = me.eventStore;
+            idEvent= me.historyId_events;
 
-        me.setSource(value, cfg.sourceConfig);
+            if (idEvent === undefined) {
+                throw "historyId_events is undefined, a bug in ExtJS 6.2.0 ?";
+            }
+
+            cfg = Event.getHistoryDataConfig(events, idEvent);
+            me.setSource(value, cfg.sourceConfig);
+        }
     }
 });