move-workspace-to-monitor: Fetch previous workspace before moving

Otherwise the previous workspace will be the workspace that just moved,
causing the "is not visible check" in `getStubWorkspace` to fail. As a
result, the moving workspace is always replaced by the first non-empty
workspace on that monitor, which is not intuitive.

Author: mattco98

Sources/AppBundle/command/impl/MoveWorkspaceToMonitorCommand.swift

@@ -15,8 +15,8 @@ struct MoveWorkspaceToMonitorCommand: Command {
                 if targetMonitor.monitorId == prevMonitor.monitorId {
                     return true
                 }
+                let stubWorkspace = getStubWorkspace(for: prevMonitor)
                 if targetMonitor.setActiveWorkspace(focusedWorkspace) {
-                    let stubWorkspace = getStubWorkspace(for: prevMonitor)
                     check(
                         prevMonitor.setActiveWorkspace(stubWorkspace),
                         "getStubWorkspace generated incompatible stub workspace (\(stubWorkspace)) for the monitor (\(prevMonitor)",