do not allow empty steps in workflows

src/pages/approval-workflows/create.tsx

@@ -124,6 +124,16 @@ export default function Home({ user, allConfiguredWorkflows, userEntitiesWithLab
             return;
         }
 
+        for (const workflow of workflows) {
+            for (const step of workflow.steps) {
+                if (step.assignees.every(x => !x)) {
+                    toast.warning("There are empty steps in at least one of the configured workflows.");
+                    setIsLoading(false); 
+                    return;
+                }
+            }
+        }
+
         const filteredWorkflows: ApprovalWorkflow[] = workflows.map(workflow => ({
             ...workflow,
             steps: workflow.steps.map(step => ({