How could be that the errors depend on the phone? I have Samsung A5 (2016). And somtimes only i cannot run the code properly.

Question

I know about it from the comments

Answer 1

The reason is the version of the Android of your phone. For ex, old devices don't support ECMA Script 6 and hence, give errors in such code while latest devices support it.

Answer 2

Android version is 7.0

Answer 3

Linking the code here may be helpful to determine the issue you're experiencing. Your webview should be up to date so I doubt it's a ES6 support issue.