Fix two union serialization defects: nullable case overload merging (#128688) and default(struct union) crash (#128834) - #128900

Fix two union serialization defects: nullable case overload merging (#128688) and default(struct union) crash (#128834)#128900

eiriktsarpalis merged 4 commits into

dotnet:maindotnet/runtime:mainfrom

eiriktsarpalis:unions/no-merge-nullable-ctor-overloadseiriktsarpalis/runtime:unions/no-merge-nullable-ctor-overloadsCopy head branch name to clipboard