Fix NPE during Editor startup in AutosaveRecovery.java (Fix #10235)

From the original report:
```
*3. Launching problem with OMERO.editor on a Windows system*

OMERO.editor can't be launched. The problem looks similar to this one : 
http://trac.openmicroscopy.org.uk/ome/ticket/10235
The user really wants to try the application. Any help ?
/Error Log attached to this mail as //_OMERO.editor_Error.log_/
```
Follow-up:
```
The editor client was running Windows 7 (32 bit) with a non-administrator
local account (also the %USERPROFILE%\omero directory seemed to be missing
for some reason, but without breaking other clients).
```

/cc @zeb