Improve "Prefix record insertion error:" assertion error

[travishathaway]

Checklist

• I added a descriptive title
• I searched open reports and couldn't find a duplicate

What happened?

Every once in a while we get users reporting the assertion error raised here:

conda/conda/core/prefix_data.py

Lines 103 to 107 in ac59821

	assert prefix_record.name not in self._prefix_records, (
	"Prefix record insertion error: a record with name %s already exists "
	"in the prefix. This is a bug in conda. Please report it at "
	"https://github.com/conda/conda/issues" % prefix_record.name
	)

Here are the following issues that have reported it:

• Assertion Error #12822
• AssertionError while installing Selenium using Condo #12405
• AssertionError('Prefix record insertion error: a record with name ca-certificates already exists in the prefix.) #12339
• 'ipykernel' can not be installed #11587
• Prefix record insertion error: a record with name _libgcc_mutex already exists in the prefix. #11565

What should happen?

I think the better solution would be to replace this assertion error with an actual conda error. Furthermore, we should also provide some sort of actionable advice. I believe that this error could be overcome by simply removing and recreating the environment. If it's the base environment, we will want to recommend another action (perhaps reverting it to an early state).

No matter what happens, I do not want a message there that instructs users to create new issues in this queue without giving any advice on how they may be able to fix it.

Additional context

I also think that it would be safe to close the issues linked above once we have completed this issue.