improve error reporting in some cases

[alexander-akait]

• Operating System: any
• Node Version: any
• NPM Version: any
• webpack Version: any
• schema-utils Version: 2.0.0

Feature Proposal

Supports:

• better errors for not keyword, for example ({ "not": { "minimum": 3 } } should output should not be < 3 | should be any non-number)
• improve message for objects like object { key: string }

Feature Use Case

Better error reporting

[vankop]

@evilebottnawi I think it will be better, if you will describe what you mean in 2nd proposal

[alexander-akait]

@vankop
Now https://github.com/webpack/schema-utils/blob/master/test/__snapshots__/index.test.js.snap#L1544

Expected: object { foo?: boolean, bar?: integer } (boolean and integer just example maybe in test should be other value).

Also printing objects now is very unreadable when we have a lot of properties, will be great break them in style:

object { 
  bar1, 
  bar2,
  bar3, 
  bar4, 
  bar5, 
  bar6, 
  bar7 
}

But it is other issue

[vankop]

i will take second one, if you did not start it =)

[alexander-akait]

Feel free to send a PR 👍