Wrong column on duplicated mapping key exception

[hughsw]

On this file containing 164 bytes:

VendorContact:
  fields:
    EntityContact: belongsTo

VendorContact:
  fields:
    ContactPerson: belongsTo

This exception:

YAMLException: duplicated mapping key at line 5, column -53:
    VendorContact:
    ^

Column should be 1.

Column calculation appears to be based on offset in some buffer (in this case the distance to the end of the file) rather than the parser position, modulo sign and off-by-one:
Bytes from start of duplicate to end of file: 54

safeLoad()
"js-yaml": "3.12.0",

See also #243 for links to a related, but fixed issue.

[rlidwka]

Fixed in b1cc0e9 (currently in dev branch, gonna be released as js-yaml 4 later).