Unhandled error message on the Grid in Metadata Management for completely new environments

[akaliahin]

Unhandled error message on the Grid in Metadata Management window appears in case if you switch between environments and don't "Save All" before going to Metadata management window.
Steps to reproduce:

1. Open TEAM
2. Navigate to Configuration -> Settings windows
3. On "Environments" tab create new environment
4. Modify all required attributes (Paths, Data Warehouse, Data Object Types, Connections)
5. Save environment
6. Switch to old environment
7. Save All
8. Switch to "newly created" environment
9. Close configuration window without saving
10. Open Metadata Management

Expected behaviour: no errors

Actual behaviour: Unhandled error message