fix: 修复抖音支付双端UTS编译兼容

uni_modules/tb-douyin-pay/utssdk/common.uts

@@ -1,4 +1,4 @@
-import { PayOptions, PayCallback, PayResult } from './interface.uts'
+import { PayInfo, PayOptions, PayCallback, PayResult } from './interface.uts'
 
 let appId = ''
 let busy = false
@@ -24,12 +24,25 @@ export function invoke(options: PayOptions, callback: PayCallback,
     return
   }
   let valid = false
+  let payload: string = ''
   try {
-    const info = options.payInfo
-    const values = [info.appid, info.partnerid, info.prepayid, info.package, info.noncestr, info.timestamp, info.sign]
-    valid = appId.length > 0 && info.appid == appId && info.package == 'Sign=DYPay'
-    values.forEach((value: string) => { if (value.trim().length == 0) valid = false })
-    if (!/^[0-9]{1,10}$/.test(info.timestamp) || info.noncestr.length > 32) valid = false
+    // Swift infers an optional from the generated PayInfo! property unless
+    // the local type is explicit. Check before narrowing on both platforms.
+    const candidate: PayInfo | null = options.payInfo
+    if (candidate != null) {
+      const info: PayInfo = candidate as PayInfo
+      const values = new Array<string>(info.appid ?? '', info.partnerid ?? '', info.prepayid ?? '',
+        info.package ?? '', info.noncestr ?? '', info.timestamp ?? '', info.sign ?? '')
+      valid = appId.length > 0 && values[0] == appId && values[3] == 'Sign=DYPay'
+      values.forEach((value: string) => { if (value.trim().length == 0) valid = false })
+      if (!/^[0-9]{1,10}$/.test(values[5]) || values[4].length > 32) valid = false
+      // UTS JSON.stringify returns string | null. Serialize before taking the
+      // payment lock, and never pass a nullable value to a native String API.
+      if (valid) {
+        payload = JSON.stringify(info) ?? ''
+        if (payload.length == 0) valid = false
+      }
+    }
   } catch (e) { valid = false }
   if (!valid) {
     const result: PayResult = { resultCode: '-1', errorMsg: '支付参数不完整或 AppID 不匹配，请重新下单', needsQuery: false }
@@ -61,7 +74,7 @@ export function invoke(options: PayOptions, callback: PayCallback,
     callback(result)
   }
   try {
-    nativePay(JSON.stringify(options.payInfo), options.showLoading ?? true, complete)
+    nativePay(payload, options.showLoading ?? true, complete)
   } catch (e) {
     complete('{"resultCode":"2","errorMsg":"无法调用支付 SDK，请查询订单后重试"}')
   }