Handle errors from Yarn Berry more gracefully

[sargunv]

Currently, if yarn npm audit has some error (other than detected vulns), audit-ci with fail with an error like this:

Uncaught Error: Invalid JSON (Unexpected "I" at position 0 in state STOP)

Instead, audit-ci's thrown error message should probably include some info about the error Yarn reported.

I ran into this in #298 , and also when trying to bump the tested Yarn version in PR #300 (CI link here)

[quinnturner]

I am pretty sure this is the case for all package managers. Since every package manager implementation attempts to JSON.parse, we can probably use consistent behaviour.

Perhaps we just wrap all JSON.parse for all package managers in a try/catch and rethrow the error to include the response itself?

[quinnturner]

Closed with #306, released in v6.6.1