I found a crash report on Crashlytics in a Samsung SM G920F (Galaxy S6), version 5.1.1 (on all other devices I didn\'t retrieve same error).
java.lang.Runtim
It seems that something strange ocurred when the app was inflating the WebView, could be whatever.
For the NameNotFoundException: com.google.android.webview I can deduce that could be a problem with the Google packages (The user could be using a custom ROM and not having them installed.)
If you had more info about the terminal with the error I'll say you go for it, but you have to see the proportion of users/users_with_this_error that you have. Then you could see if it's useful for you work in this issue or not.
From breakline's comment: Check out this post, looks kinda like the same issue: NameNotFoundException webview