javascript - Uncaught TypeError: Cannot read property 'isSynchronized' of undefined -

i have problem sorting extjs grid. i'm using ext js version 5.1.1.451.

the grid loads when try sort columns "uncaught typeerror: cannot read property 'issynchronized' of undefined" error.

the method addcls triggered on mouse movement , when error occures, me.getdata() returns undefined, me

constructor $observableinitialized: true component: constructor config: object destroy: () {} dom: null el: null events: object haslisteners: statics.prepareclass.haslisteners id: "ext-quicktips-tip" initconfig: () {} initialconfig: object isdestroyed: true lastbox: null managedlisteners: array[0] shadow: null 

this addcls method error occurs:

addcls: function(names, prefix, suffix) {         var me = this,             elementdata = me.getdata(),             hasnewcls, dom, map, classlist, i, ln, name;         if (!names) {             return me;         }         if (!elementdata.issynchronized) {             me.synchronize();         } 

has encounter problem before? known issue or doing wrong?

thank you

i've overriden handlemousedown method , commented out quick tips part.

ext.override(ext.dd.dragdropmanager, {     handlemousedown: function (e, odd) {         var me = this,             xy, el;         me.ismousedown = true;         //if (ext.quicktipsactive) {         //    ext.tip.quicktipmanager.dddisable();         //}         me.currentpoint = e.getpoint();         if (me.dragcurrent) {             me.handlemouseup(e);         }         me.mousedownevent = e;         me.currenttarget = e.gettarget();         me.dragcurrent = odd;         el = odd.getel();           ext.fly(el).setcapture();           xy = e.getxy();         me.startx = xy[0];         me.starty = xy[1];           me.offsetx = me.offsety = 0;         me.deltax = me.startx - el.offsetleft;         me.deltay = me.starty - el.offsettop;         me.dragthreshmet = false;     } }); 

if has better answer, post , mark if it's good.