CLI import-based commands fail with too few information on importing COCO directory with different categories in files

[zhiltsov-max]

test_coco_error_reporting.zip

Download, unzip, run info command:

$ datum info "test/:coco_person_keypoints"
ERROR:root:Failed to parse revspec:
  Can't find project at 'Failed to find project at 'test/'. Specify project path with '-p/--project' or in the target pathspec.'
  Failed to import dataset 'coco_person_keypoints' at 'test/'.

Changing

datumaro/src/datumaro/cli/util/errors.py

Line 15 in 0ef0f02

class WrongRevpathError(CliException):

to:

@attrs
class WrongRevpathError(CliException):
    problems = attrib()

    def __str__(self):
        return "Failed to parse revspec:\n  " + "\n  ".join(str(getattr(p, "__cause__") or p) for p in self.problems)

Allows to improve the returned message:

$ datum info "test/:coco_person_keypoints"
ERROR:root:Failed to parse revspec:
  Can't find project at 'Failed to find project at 'test/'. Specify project path with '-p/--project' or in the target pathspec.'
  Merging of datasets with different categories is only allowed in 'merge' command.

It still can be better, but it already helps to understand the problem.