fix: workflow 'when' should return T or undefined instead of Partial<T> (#8195)

* fix: workflow 'when' should return T or undefined instead of Partial<T>

* fix when usage

packages/core/core-flows/src/order/workflows/claim/claim-request-item-return.ts

@@ -7,11 +7,11 @@ import {
 } from "@medusajs/types"
 import { ChangeActionType, OrderChangeStatus } from "@medusajs/utils"
 import {
-  WorkflowData,
   createStep,
   createWorkflow,
   transform,
   when,
+  WorkflowData,
 } from "@medusajs/workflows-sdk"
 import { useRemoteQueryStep } from "../../../common"
 import { createOrderChangeActionsStep } from "../../steps/create-order-change-actions"
@@ -88,7 +88,7 @@ export const orderClaimRequestItemReturnWorkflow = createWorkflow(
     const orderReturn: ReturnDTO = transform(
       { createdReturn, existingOrderReturn, orderClaim },
       ({ createdReturn, existingOrderReturn, orderClaim }) => {
-        return existingOrderReturn ?? (createdReturn[0] as ReturnDTO)
+        return existingOrderReturn ?? (createdReturn?.[0] as ReturnDTO)
       }
     )
 
@@ -130,7 +130,7 @@ export const orderClaimRequestItemReturnWorkflow = createWorkflow(
       const createdReturnId = transform(
         { createdReturn },
         ({ createdReturn }) => {
-          return createdReturn[0]!.id
+          return createdReturn?.[0]!.id
         }
       )
       updateOrderClaimsStep([

packages/core/core-flows/src/order/workflows/exchange/exchange-request-item-return.ts

@@ -7,11 +7,11 @@ import {
 } from "@medusajs/types"
 import { ChangeActionType, OrderChangeStatus } from "@medusajs/utils"
 import {
-  WorkflowData,
   createStep,
   createWorkflow,
   transform,
   when,
+  WorkflowData,
 } from "@medusajs/workflows-sdk"
 import { useRemoteQueryStep } from "../../../common"
 import { createOrderChangeActionsStep } from "../../steps/create-order-change-actions"
@@ -89,7 +89,7 @@ export const orderExchangeRequestItemReturnWorkflow = createWorkflow(
     const orderReturn: ReturnDTO = transform(
       { createdReturn, existingOrderReturn, orderExchange },
       ({ createdReturn, existingOrderReturn, orderExchange }) => {
-        return existingOrderReturn ?? (createdReturn[0] as ReturnDTO)
+        return existingOrderReturn ?? (createdReturn?.[0] as ReturnDTO)
       }
     )
 
@@ -128,7 +128,7 @@ export const orderExchangeRequestItemReturnWorkflow = createWorkflow(
       const createdReturnId = transform(
         { createdReturn },
         ({ createdReturn }) => {
-          return createdReturn[0]!.id
+          return createdReturn?.[0]!.id
         }
       )
       updateOrderExchangesStep([

packages/core/workflows-sdk/src/utils/composer/when.ts

@@ -13,7 +13,7 @@ type ConditionFunction<T extends object | WorkflowData> = (
 type ThenFunc = <ThenResolver extends () => any>(
   resolver: ThenResolver
 ) => ReturnType<ThenResolver> extends WorkflowData<infer ReturnedWorkflowData>
-  ? Partial<WorkflowData<ReturnedWorkflowData>>
+  ? WorkflowData<ReturnedWorkflowData> | undefined
   : ReturnType<ThenResolver>
 
 export function when<T extends object | WorkflowData, Then extends Function>(