JS Error fires on row click

[sachin sachdeva]

Hello Sir
I am using Property grid and Json data to populate that grid now issue is when i edit a property grid by entering data in cells and then click on next row it is working fine but when i double click the property grid cell it enters into editable mode and if i do not put data in that cell and clicks on next row it fires a js error 'this.getRow(...)' is null or not an object .Rest of the information you can find in my screen shots.My code is given below

GeneralpropsGrid code
GeneralpropsGrid = new Ext.grid.PropertyGrid(
                                            {
                                                title : 'General Properties',
                                                isEditable : true,
                                                loadMask : {
                                                    hideOnReady : false
                                                },
                                                listeners : {
                                                    beforeedit : function(
                                                            rowIndex, grid) {
                                                        return this
                                                                .checkIfEditable(rowIndex.record.id);
                                                    }
                                                }
.
.
. 

Json data code
grid.on('rowclick', updateProps);

            function updateProps(grid, dataIndex) {
                
                var dataRow = grid.getSelectionModel().getSelected();


                source = "{" + "\"Size\":\" " + dataRow.data.size + "\"," + ""
                        + "\"Author\":\"" + author+ "\"," + ""
                        + "\"File Name\":\"" + dataRow.data.fileName + "\" ,"
                        + "" + "\"Title\":\"" + title + "\" ,"
                        + "" + "\"Extension\":\"" + fileExtension + "\" ," + ""
                        + "\"Release Date\":\"" + releaseDate + "\" ,"
                        + "\"Expiration Date\":\"" + expirationDate + "\" ,"
                        + "" + "\"Searchable\":\"" + dataRow.data.searchable
                        + "\" ," + "" + "\"Tags\":\"" + tags
                        + "\" ," + "" + "\"Content Category\":\""
                        + dataRow.data.contentCategory + "\" ," + ""
                        + "\"Comments\":\"" + comments + "\" ,"
                        + "" + "\"Websites\":\"" + dataRow.data.websites
                        + "\" " + "}";
            

              

               
                GeneralpropsGrid.setSource(eval('(' + source + ')'));
            }