Report errors when loading migration file fails

[jesstelford]

For example, I did something silly and used await at the top level:

await Promise.resolve(true);

module.exports = {
  up(db) { /* .. */ },
  up(db) { /* .. */ },
};

This change catches the error and reports it as a failed migration.

Checklist

• npm test passes and has 100% coverage

[coveralls]

Coverage remained the same at 100.0% when pulling 88f7430 on jesstelford:patch-2 into f729842 on seppevs:master.

[coveralls]

Coverage remained the same at 100.0% when pulling 88f7430 on jesstelford:patch-2 into f729842 on seppevs:master.

[seppevs]

Landed in v4.1.1 🎉
Thank you for your contribution.