[All] spec 1.2 doesn't WARN or ERROR on invalid template

Description

Swagger-codegen version

v2.2.3

Swagger declaration file content or url

{   "apiVersion": "0.1",
    "apis": [
        { "operations": [{"method": "GET", "nickname": "testGet"} ],
          "path": "/test"
        }
    ],
    "models": {
        "MyError": {
            "properties": {
                "fields": {
                    "description": ["Arrays in the description seems to break the generator"],
                    "type": "object"
                }
            }
        }
    },
    "resourcePath": "/test",
    "swaggerVersion": "1.2"
}

Command line used for generation

swagger-codegen generate -i bareminimum.json -o bm1 -l go

Steps to reproduce

1. Run the command
2. Notice that it does not generate a my_error.go class nor does it throw a warning or an error
3. Change the "description" value to a string
4. Rerun the command
5. Notice that it does generate a my_error.go class

Related issues/PRs

I closed #6811 and opened this, more general, issue. This issue seems similar to #5312 in that it is a parsing error with 1.2 spec.

Suggest a fix/enhancement

I suspect that the 1.2 spec parsing is swallowing errors/warnings somewhere. It would be great to expose these messages so that offending spec files can be more easily corrected.

Start by running swagger-codegen generate -i bareminimum.json -o bm1 -l go with the supplied Swagger 1.2 declaration and compare it with the version whose description is a string. Trace the 1.2 parsing and template-generation path for how the invalid array value is handled; done means the invalid template produces a visible warning or error instead of silently omitting my_error.go.