fix(WorkflowSteps): fixed how hooks are invoked + added support for '…

…onExit' hook (#4568)

platform/core/src/services/WorkflowStepsService/WorkflowStepsService.ts

@@ -77,6 +77,7 @@ export type WorkflowStep = {
     };
   };
   onEnter: () => void | CommandCallback[];
+  onExit: () => void | CommandCallback[];
 };
 
 class WorkflowStepsService extends PubSubService {
@@ -172,7 +173,7 @@ class WorkflowStepsService extends PubSubService {
 
     const commandsManager = this._commandsManager;
 
-    if (!Array.isArray) {
+    if (!Array.isArray(callbacks)) {
       callbacks = [callbacks];
     }
 
@@ -203,6 +204,10 @@ class WorkflowStepsService extends PubSubService {
       throw new Error(`Invalid workflowStepId (${workflowStepId})`);
     }
 
+    if (this._activeWorkflowStep) {
+      this._invokeCallbacks(previousWorkflowStep.onExit);
+    }
+
     // onEnter needs to be called before updating the Hanging Protocol because
     // some displaySets need to be created before moving to the next HP stage
     // (eg: convert segmentations into a chart displaySet). If needed we can