fix(api): harden notification assignee persistence

packages/api/src/__tests__/notification-procedure-support.test.ts

@@ -82,6 +82,24 @@ describe("notification procedure support", () => {
     }
   });
 
+  it("rewrites assignee foreign-key errors to a not found TRPC error", () => {
+    const error = {
+      code: "P2003",
+      meta: { field_name: "Notification_assigneeId_fkey" },
+    };
+
+    try {
+      rethrowNotificationReferenceError(error);
+      throw new Error("expected notification reference error");
+    } catch (caught) {
+      expect(caught).toBeInstanceOf(TRPCError);
+      expect(caught).toMatchObject<Partial<TRPCError>>({
+        code: "NOT_FOUND",
+        message: "Assignee user not found",
+      });
+    }
+  });
+
   it("rewrites broadcast source foreign-key errors to a not found TRPC error", () => {
     const error = {
       code: "P2003",