anchor.diff:    static final DataError accessorInvalidSign = new DataError._(
         'ACCESSOR_INVALID_SIGN',
         (args) => 'Accessor element at index ${args[0]} '
  -          'has w component with invalid sign: ${args[1]}.');
  +          'has invalid w component: ${args[1]}. Must be 1.0 or -1.0.');
   
     static final DataError accessorInvalidFloat = new DataError._(
         'ACCESSOR_INVALID_FLOAT',
  
positive.code:       'NODE_MATRIX_NON_TRS', (args) => 'Matrix must be decomposable to TRS.');
  
    static final SemanticError nodeRotationNonUnit = new SemanticError._(
        'NODE_ROTATION_NON_UNIT', (args) => 'Rotation quaternion must be normalized.');
  
    static final SemanticError unusedExtensionRequired = new SemanticError._(
        'UNUSED_EXTENSION_REQUIRED',
  
negative.code:       'IMAGE_UNEXPECTED_EOS', (args) => 'Unexpected end of image stream.');
  
    static final DataError imageUnrecognizedFormat = new DataError._(
        'IMAGE_UNRECOGNIZED_FORMAT', (args) => 'Image format not recognized.');
  
    static final DataError imageNonPowerOfTwoDimensions = new DataError._(
        'IMAGE_NPOT_DIMENSIONS',
  