修复uni-installApk语法校验警告

(cherry picked from commit 84fee7f0)

uni_modules/uni-installApk/utssdk/unierror.uts

@@ -15,7 +15,8 @@ export const UniErrors : Map<InstallApkErrorCode, string> = new Map([
 	[1300002, 'No such file'],
 ]);
 
-export class InstallApkFailImpl extends UniError implements InstallApkFail {
+export class InstallApkFailImpl extends UniError implements InstallApkFail {
+  override errCode : InstallApkErrorCode
 	constructor(errCode : InstallApkErrorCode) {
 		super();
 		this.errSubject = UniErrorSubject;