feat: Preserver previous state on async error

[rrousselGit]

No description provided.

[codecov]

Codecov Report

Merging #2025 (299d366) into master (06f98c2) will increase coverage by 0.19%.
The diff coverage is 100.00%.

❗ Current head 299d366 differs from pull request most recent head 15bf939. Consider uploading reports for the commit 15bf939 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2025      +/-   ##
==========================================
+ Coverage   96.21%   96.40%   +0.19%     
==========================================
  Files          48       48              
  Lines        2010     2033      +23     
==========================================
+ Hits         1934     1960      +26     
+ Misses         76       73       -3     

Impacted Files	Coverage Δ
packages/riverpod/lib/src/async_notifier.dart	100.00% <ø> (ø)
packages/riverpod/lib/src/listenable.dart	61.29% <ø> (ø)
packages/riverpod/lib/src/async_notifier/base.dart	100.00% <100.00%> (ø)
packages/riverpod/lib/src/common.dart	100.00% <100.00%> (ø)
packages/riverpod/lib/src/framework/element.dart	98.22% <100.00%> (ø)
...ackages/riverpod/lib/src/future_provider/base.dart	100.00% <100.00%> (ø)
packages/riverpod/lib/src/stream_provider.dart	100.00% <100.00%> (ø)
...ackages/riverpod/lib/src/stream_provider/base.dart	100.00% <100.00%> (+3.94%)	⬆️