6.5: Group record passed to Ext.data.field.Field convert while depends field is nul

[shmeltex]

In 6.5.x when Store with groupField based on the result of calculated field is used, grouping record is being passed to convert method and causes an exception since depends configuration is ignored. In 6.2.x it worked as expected - only records with non-empty field configured in depends are being passed to convert method and grouping records were obeying depends config as well.
Fiddle with an example: https://fiddle.sencha.com/#view/editor&fiddle/23e1. It works when 6.2 framework is selected and throws an exception in 6.5.

[Gary Schlosberg]

Thanks for the report. We're tracking this one as EXTJS-25920.