Better handling of new Error(string) throughout the pipeline(s). Fixes #1338, #1486

[indexzero]

There are 14 distinct entry-points for this. They are now tracked by test/formats/errors.test.js:

  format.errors (integration)
    ✓ logger.log(level, error)
    ✓ logger.log(level, error) [custom error properties]
    ✓ logger.log(level, error, meta)
    ✓ logger.log(level, error, meta) [custom error properties]
    ✓ logger.log(level, msg, meta<error>)
    ✓ logger.log(level, msg, meta<error>) [custom error properties]
    ✓ logger.<level>(error)
    ✓ logger.<level>(error) [custom error properties]
    ✓ logger.<level>(error, meta)
    ✓ logger.<level>(error, meta) [custom error properties]
    ✓ logger.<level>(msg, meta<error>)
    ✓ logger.<level>(msg, meta<error>) [custom error properties]
    ✓ Promise.reject().catch(logger.<level>)
    ✓ Promise.reject().catch(logger.<level>) [custom error properties]

This also adds new semantics to winston related to (and also fixing) #1486. From the updated README.md:

NOTE: any { message } property in a meta object provided will
automatically be concatenated to any msg already provided: For
example the below will concatenate 'world' onto 'hello':

logger.log('error', 'hello', { message: 'world' });
logger.info('hello', { message: 'world' });

This is need specifically for these use-cases:

logger.log('level', 'Any string', new Error('ok sure why'));
logger.error('Any string', new Error('ok sure why'));

The other cases are all handled by winston.formats.errors() and depend on winstonjs/logform#69.

[kibertoad]

Also tests are failing.

[indexzero]

@kibertoad the previous test failure was by design since this depended on winstonjs/logform#69 being merged & published (now available in logform@2.1.0).

The comment about defaultMeta is most likely a bug, but could be fixed post merge. Feel free to take it on if you'd like.

[indexzero]

Decided to switch the order of the merge. Should address the concerns you mentioned @kibertoad.

[kibertoad]

LGTM!

[gaastonsr]

Once this is merged v3.2.0 will be published? :) can't wait.