Validation of substituted content (as effect of resolving `$ref`s) leads to confusing error reports

[nartamonov]

Is your feature request related to a problem? Please describe. Validation of substituted content (as effect of resolving $refs) leads to confusing error reports.

For example, we have the following spec:

openapi: 3.0.3
servers:
  - url: //example.com/api
    description: Production
info:
  version: '1.0'
  title: Sample API spec
paths:
  /something:
    post:
      summary: Post something
      operationId: postSomething
      requestBody:
        $ref: '#/components/schemas/SomethingSpec'
      responses:
        '204':
          description: Response
components:
  schemas:
    SomethingSpec:
      description: Something
      properties:
        name:
          type: string

That spec has invalid syntax of requestBody block (line 14), but otherwise perfectly valid SomethingSpec schema. Instead validator reports that we have problems with SomethingSpec schema (at lines 21 and 23):

λ docker run --rm -it -v v1.yaml:/v1.yaml redocly/openapi-cli:v1.0.0-beta.67 lint /v1.yaml
No configurations were defined in extends -- using built in recommended configuration by default.                                              
                                                                                                                                               
validating /v1.yaml...                                                                                                                         
[1] ../v1.yaml:21:5 at #/components/schemas/SomethingSpec                                                                                      
                                                                                                                                               
The field `content` must be present on this level.                                                                                             
                                                                                                                                               
19 | components:                                                                                                                               
20 |   schemas:                                                                                                                                
21 |     SomethingSpec:                                                                                                                        
22 |       description: Something                                                                                                              
23 |       properties:                                                                                                                         
                                                                                                                                               
Error was generated by the spec rule.                                                                                                          
                                                                                                                                               
                                                                                                                                               
[2] ../v1.yaml:23:7 at #/components/schemas/SomethingSpec/properties                                                                           
                                                                                                                                               
Property `properties` is not expected here.                                                                                                    
                                                                                                                                               
21 | SomethingSpec:                                                                                                                            
22 |   description: Something                                                                                                                  
23 |   properties:                                                                                                                             
24 |     name:                                                                                                                                 
25 |       type: string                                                                                                                        
                                                                                                                                               
Error was generated by the spec rule.                                                                                                          

I got similar problem with rather big OpenAPI spec and spent much time to figure out why validator says that my schemas is incorrect when it is obvious they are good.

Describe the solution you'd like I think validator should explicitly point out real context of the specification which have some problems in it. In the demonstrated case it is not the schema object, but requestBody (after substitution of the content of SomethingSpec).