Context and problem to solve

Currently guru will abort if any package in the scope has some I/O, parser or type error. There is no way to disable this behaviour.

guru is used for multiple plugins in different editors and IDEs (e.g. vim-go, vscode-go, go-plus for atom). In development environments it is common to be used in code trees where there might be files which some errors, missing dependencies, etc.

It is quite inconvenient not be able to use guru for code analysis simply because some .go fails. It would be desirable if guru had some option to ignore such error, ignoring the package during analysis.

Proposal

I propose add an option -allowerrors which would enable the flag loader.Config.AllowErrors:

If AllowErrors is true, Load will return a Program even
if some of the its packages contained I/O, parser or type
errors; such errors are accessible via PackageInfo.Errors. If
false, Load will fail if any package had an error.

With this option guru will still print the errors in stderr, but ignore the packages with errors and perform the analysis.