[validate] Report details of data validation errors

[rufuspollock]

Running data validate gives error messages like this but without listing the actual error:

> Error! There are 1 type and format mismatch errors (see 'error.errors')

This is not very helpful as i can't fix the error.

Tasks

• Change data validate to report errors in detail

Analysis

• ?? where can i find documentation of the error structure from tableschema-js ...
  • I thought it might be like the stuff from goodtables e.g. https://github.com/frictionlessdata/goodtables-ui/blob/master/data/report.json
  • I tried reading: https://github.com/frictionlessdata/goodtables-ui and got lost ...

OK: finally tracked it down - https://github.com/frictionlessdata/tableschema-js/blob/master/src/table.js#L100

try {
  row = this.schema.castRow(row)
} catch (error) {
  error.rowNumber = rowNumber
  error.errors.forEach(error => {error.rowNumber = rowNumber})
  throw error
}

Note: there also header errors that have a slightly different structure afaict ... https://github.com/frictionlessdata/tableschema-js/blob/master/src/table.js#L102

The errors here are TableSchemaError.

[rufuspollock]

FIXED. Note:

• I think some work may be needed on tableschema-js to improve this. e.g. we only find the first error and reports don't make the goodtables report structure
• Also not sure i handle header errors
• No testing of this (it is output stuff ...)