There are several kinds of errors or exceptions in go_router.
This kind of errors are thrown when go_router is used incorrectly, for example, if the root GoRoute.path does not start with / or a builder in GoRoute is not provided. These errors should not be caught and must be fixed in code in order to use go_router.
This kind of exception are thrown when the configuration of go_router cannot handle incoming requests from users or other part of the code. For example, an GoException is thrown when user enter url that can't be parsed according to pattern specified in the GoRouter.routes. These exceptions can be handled in various callbacks.
Once can provide a callback to GoRouter.onException to handle this exception. In this callback, one can choose to ignore, redirect, or push different pages depending on the situation. See Exception Handling on a runnable example.
The GoRouter.errorBuilder and GoRouter.errorPageBuilder can also be used to handle exceptions.
GoRouter( /* ... */ errorBuilder: (context, state) => ErrorScreen(state.error), );
By default, go_router comes with default error screens for both MaterialApp and CupertinoApp as well as a default error screen in the case that none is used.
Note the GoRouter.onException supersedes other exception handling APIs.