getErrors method
Get error messages associated with form attributes.
The getErrors function is used to retrieve error messages associated
with form attributes that have errors. It creates a copy of the _errors map,
removes entries for attributes that do not exist in the _attributes map, and
returns the resulting map of attribute-error message pairs.
Returns: A map of form attribute identifiers to lists of error messages.
Implementation
Map<String, List<String>> getErrors() {
final Map<String, List<String>> errors = Map.from(_errors);
errors.removeWhere((key, value) => !_attributes.containsKey(key));
return errors;
}