fix: Hanging protocol state fixes (#3242)

* fix: Some residual issues with hanging protocol after state sync

fix: Some issues introduced by the state syncing changes

* fix: PR fixes, mostly code cleanup

* Improve a race condition in an automated test

* Remove obsolete code

* PR fixes

platform/core/src/services/StateSyncService/StateSyncService.ts

@@ -42,6 +42,12 @@ export default class StateSyncService extends PubSubService {
 
   public init(extensionManager: ExtensionManager): void { }
 
+  /** Registers a new sync store called `id`.  The state
+   * defines how the state is stored, and any default clearing of the
+   * state.
+   * A default store has the lifetime of the application.
+   * The other available store is cleared `onModeExit`
+   */
   public register(id: string, config: StateConfig): void {
     this.registeredStateSets[id] = config;
     this.store({ [id]: {} });

platform/core/src/types/HangingProtocol.ts

@@ -141,8 +141,8 @@ export type initialImageOptions = {
 };
 
 export type ViewportOptions = {
-  toolGroupId: string;
-  viewportType: string;
+  toolGroupId?: string;
+  viewportType?: string;
   id?: string;
   orientation?: string;
   viewportId?: string;