Import errors in default plugins are difficult to find

[jholecek-rh]

This is a follow-up to #3405.

I was kind of lucky to find the root cause of #3405. insights run has no command line arguments that would reveal why there was a missing dependency. The reason is that insights.specs.default is effectively loaded by insights.load_default_plugins() with continue_on_error=True outside of the -p imports.

I'm curious what is the purpose of hardcoded default plugins. I view insights-core as a generic engine that enables plugins to analyze application-specific data. The hardcoded default packages will be inevitably irrelevant for applications that insights-core is not aware of (e.g. OCP4 rules). Application-specific defaults can be provided in the configuration file.

Assuming there are reasons to load the hardcoded default plugins, I wonder why they are imported with continue_on_error=True. I would expect that the plugins, being part of insights-core, should always be importable in a properly installed environment. It would do no harm to load them with continue_on_error=False, plus it would make troubleshooting easier should they fail to import in a particular environment (e.g. a corrupted one).