Handle didUpdateWidget for _StackNavigator when using a global key

[josephelliot-wk]

Problem

We found a bug where using a GlobalKey for the PageStackNavigator.navigatorKey causes the internal _StackNavigator to fail to re-assign itself to the internal page stack. This issue presented itself as the Android back button failing to close non-routemaster routes (like a bottom sheet) and instead just closing the entire app.

Inside the PageStackNavigatorState, any time the PageStack changes, it'll invoke a function that recreates the _StackNavigator widget. Without a key, this would cause the navigator widget to run initState, thus setting itself on the PageStack. However, with a key, the state object is re-used, so initState (and dispose) are never called.

This is problematic because if you provide a navigator key for hooking into the navigator throughout your app, the PageStack can change but the _StackNavigator's state functions are never called and thus pop() calls for non-routemaster routes will ultimately return false, causing the app to close.

Solution

To solve this, all we need to do is override _StackNavigatorState.didUpdateWidget and handle the scenario of the internal stack changing -- if it changes, then drop the old navigator reference and add a new navigator reference to the new page stack.

FYI @tomgilder

[codecov]

Codecov Report

Merging #318 (baf6850) into main (e6f04ec) will increase coverage by 0.00%.
The diff coverage is 100.00%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #318   +/-   ##
=======================================
  Coverage   99.40%   99.40%           
=======================================
  Files          20       20           
  Lines        1006     1015    +9     
=======================================
+ Hits         1000     1009    +9     
  Misses          6        6           

Impacted Files	Coverage Δ
lib/routemaster.dart	100.00% <100.00%> (ø)
lib/src/route_history.dart	87.75% <100.00%> (+1.70%)	⬆️
lib/src/pages/stack_page.dart	100.00% <0.00%> (ø)
lib/src/pages/indexed_page.dart	100.00% <0.00%> (ø)

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[josephelliot-wk]

Bump @tomgilder

[davidgiametta-wk]

Bump @tomgilder

[josephelliot-wk]

Bump @tomgilder

[davidgiametta-wk]

Cc @tomgilder