Snapshot error displayed as modal dialog when system is not fully configured

[mborgerson]

Bug Description

It's possible for this error message to be displayed when a user has not fully configured xemu when they click on the Snapshots setting page, because there is no disk image selected:

Expected Behavior

When the application is not configured, this error message should not be displayed as a modal dialog. Instead, the feature should just be visibly deactivated with some overlay message indicating why.

xemu Version

v0.7.127

System Information

N/A

Additional Context

No response