Add ! operator overloading for the result types.

[Dixin]

Currently the result type supports if (result) { }. https://dotnet.github.io/dotNext/features/core/result.html

However, if (!result) { } does not work.

Add the ! operator overloading for Result<T> and Result<T, TError> to support if (!result) { }.

[Dixin]

The failed checks are not related to the committed code changes.

The command could not be loaded, possibly because:
  * You intended to execute a .NET application:
      The application 'restore' does not exist.
  * You intended to execute a .NET SDK command:
      A compatible .NET SDK was not found.

##[error]Error: The process '/usr/bin/dotnet' failed with exit code 145
##[error]Packages failed to restore

[sakno]

Please change the target branch to develop.

[sakno]

Changing from master to develop is not enough. This happens because master always has squashed commits. To fix it, you need to create a branch from develop, cherry-pick your changes, then force-push to the remote branch associated with this PR.

[Dixin]

@sakno

Changing from master to develop is not enough. This happens because master always has squashed commits. To fix it, you need to create a branch from develop, cherry-pick your changes, then force-push to the remote branch associated with this PR.

Thank you for the help. It is done.

[sakno]

Thanks for your contribution!