Fixes T13663. supportsSubtypes tries to create an editable object, but this isn't always valid for PhabricatorCalendarImport. Use instanceof instead.
- Group Reviewers
- Maniphest Tasks
- T13663: TypeError when editing calendar import
- rP1965b78b34f1: Fix subtype extension support check
- Edited calendar import, tasks (2 different subtypes), and projects (2 different subtypes).
- Changed task subtypes using Change Subtype action and batch editor.
- Changed task and project subtypes using Conduit.