fix(grid):Grid service wasn't being reset (#3068)

* fix(grid):Grid service wasn't being reset

* fix(service):Fix the initial service state

Services with mode specific state differed in internal state between
initial and subsequent load.  This fix address that structurally by
allows the mode to store/manage service state, but makes the
responsibility of service state central to the service.

platform/viewer/src/components/ViewportGrid.tsx

@@ -452,6 +452,7 @@ function _getViewportComponent(
     }
   }
 
+  console.log("Can't show displaySet", SOPClassHandlerId, displaySets[0]);
   UINotificationService.show({
     title: 'Viewport Not Supported Yet',
     message: `Cannot display SOPClassId of ${displaySets[0].SOPClassUID} yet`,

platform/viewer/src/routes/Mode/Mode.tsx

@@ -312,11 +312,22 @@ export default function ModeRoute({
     });
 
     return () => {
-      extensionManager.onModeExit();
-      mode?.onModeExit({ servicesManager, extensionManager });
+      // The mode.onModeExit must be done first to allow it to store
+      // information, and must be in a try/catch to ensure subscriptions
+      // are unsubscribed.
+      try {
+        mode?.onModeExit?.({ servicesManager, extensionManager });
+      } catch (e) {
+        console.warn('mode exit failure', e);
+      }
+      // The unsubscriptions must occur before the extension onModeExit
+      // in order to prevent exceptions during cleanup caused by spurious events
       unsubscriptions.forEach(unsub => {
         unsub();
       });
+      // The extension manager must be called after the mode, this is
+      // expected to cleanup the state to a standard setup.
+      extensionManager.onModeExit();
     };
   }, [
     mode,