fix: treat missing return records as empty results

tests/return-receipt-api.test.mjs

@@ -50,3 +50,27 @@ test('return receipt API calls only the dedicated PDA routes and preserves the r
 	assert.ok(calls.every((item) => item.authorization === 'Bearer return-token'))
 	assert.ok(calls.every((item) => !Object.hasOwn(item.data || {}, 'customerId') && !Object.hasOwn(item.data || {}, 'warehouseId')))
 })
+
+test('return receipt lookup treats A0404 and HTTP 404 as empty results', async () => {
+	session.apiBase = '/overseas-api'; session.token = 'return-token'
+	let requestCount = 0
+	globalThis.uni = {
+		request(options) {
+			requestCount += 1
+			if (requestCount === 1) options.success({ statusCode: 404, data: { code: 'A0404', message: '当前仓没有待签收或签收中的退货单' }, header: {} })
+			else options.success({ statusCode: 404, data: {}, header: {} })
+		}
+	}
+	assert.equal(await startReturnReceipt('MISSING-RETURN'), null)
+	assert.deepEqual(await findReturnSkuCandidates('MISSING-SKU'), { skuCode: 'MISSING-SKU', candidates: [] })
+})
+
+test('return receipt lookup still rejects real service errors', async () => {
+	session.apiBase = '/overseas-api'; session.token = 'return-token'
+	globalThis.uni = {
+		request(options) {
+			options.success({ statusCode: 500, data: { code: 'B0500', message: '服务暂不可用' }, header: {} })
+		}
+	}
+	await assert.rejects(() => startReturnReceipt('RT-001'), (error) => error.code === 'B0500')
+})