# Buggy code
def _paths_checksums():
    """
    A dictionary of checksums addressed by relpaths collected from
    the current tree outputs.

    To help distinguish between a directory and a file output,
    the former one will come with a trailing slash in the path:

        directory: "data/"
        file:      "data"
    """

    def _to_path(output):
        return (
            str(output) if not output.is_dir_checksum else os.path.join(str(output), "")
        )

    on_working_tree = isinstance(self.tree, LocalTree)

    def _to_checksum(output):
        if on_working_tree:
            return self.cache.local.tree.get_hash(output.path_info)[1]
        return output.checksum

    def _exists(output):
        if on_working_tree:
            return output.exists
        return True

    return {
        _to_path(output): _to_checksum(output)
        for stage in self.stages
        for output in stage.outs
        if _exists(output)
    }


# Traceback (dvc.exceptions.RemoteCacheRequiredError)
2020-07-01 17:14:02,947 DEBUG: fetched: [(3,)]
2020-07-01 17:14:03,123 DEBUG: Removing output 'some_target' of stage: 'some_target.dvc'.
Importing 's3://some_bucket/some_target' -> 'some_target'
2020-07-01 17:14:03,123 DEBUG: Computed stage: 'some_target.dvc' md5: '2f8b87d3b22efd1638f414c3b3f65614'
2020-07-01 17:14:03,123 DEBUG: 'md5' of stage: 'some_target.dvc' changed.
2020-07-01 17:14:04,088 DEBUG: fetched: [(0,)]
2020-07-01 17:14:04,146 ERROR: failed to import s3://some_bucket/some_target. You could also try downloading it manually, and adding it with `dvc add`. - Current operation was unsuccessful because 's3://some_bucket/some_target' requires existing cache on 's3' remote. See <https://man.dvc.org/config#cache> for information on how to set up remote cache.
------------------------------------------------------------
Traceback (most recent call last):
File "/usr/lib/python3.8/site-packages/dvc/command/imp_url.py", line 14, in run
self.repo.imp_url(
File "/usr/lib/python3.8/site-packages/dvc/repo/__init__.py", line 36, in wrapper
ret = f(repo, *args, **kwargs)
File "/usr/lib/python3.8/site-packages/dvc/repo/scm_context.py", line 4, in run
result = method(repo, *args, **kw)
File "/usr/lib/python3.8/site-packages/dvc/repo/imp_url.py", line 54, in imp_url
stage.run()
File "/home/anotherbugmaster/.local/lib/python3.8/site-packages/funcy/decorators.py", line 39, in wrapper
return deco(call, *dargs, **dkwargs)
File "/usr/lib/python3.8/site-packages/dvc/stage/decorators.py", line 35, in rwlocked
return call()
File "/home/anotherbugmaster/.local/lib/python3.8/site-packages/funcy/decorators.py", line 60, in __call__
return self._func(*self._args, **self._kwargs)
File "/usr/lib/python3.8/site-packages/dvc/stage/__init__.py", line 424, in run
sync_import(self, dry, force)
File "/usr/lib/python3.8/site-packages/dvc/stage/imports.py", line 29, in sync_import
stage.save_deps()
File "/usr/lib/python3.8/site-packages/dvc/stage/__init__.py", line 387, in save_deps
dep.save()
File "/usr/lib/python3.8/site-packages/dvc/output/base.py", line 268, in save
self.info = self.save_info()
File "/usr/lib/python3.8/site-packages/dvc/output/base.py", line 192, in save_info
return self.remote.save_info(self.path_info)
File "/usr/lib/python3.8/site-packages/dvc/remote/base.py", line 762, in save_info
return self.tree.save_info(path_info, **kwargs)
File "/usr/lib/python3.8/site-packages/dvc/remote/base.py", line 329, in save_info
self.PARAM_CHECKSUM: self.get_hash(path_info, tree=tree, **kwargs)
File "/usr/lib/python3.8/site-packages/dvc/remote/base.py", line 297, in get_hash
hash_ = self.get_dir_hash(path_info, tree, **kwargs)
File "/usr/lib/python3.8/site-packages/dvc/remote/base.py", line 311, in get_dir_hash
raise RemoteCacheRequiredError(path_info)
dvc.exceptions.RemoteCacheRequiredError: Current operation was unsuccessful because 's3://some_bucket/some_target' requires existing cache on 's3' remote. See <https://man.dvc.org/config#cache> for information on how to set up remote cache.
------------------------------------------------------------

Having any troubles? Hit us up at https://dvc.org/support, we are always happy to help!

# Fixed code
def _paths_checksums():
    """
    A dictionary of checksums addressed by relpaths collected from
    the current tree outputs.

    To help distinguish between a directory and a file output,
    the former one will come with a trailing slash in the path:

        directory: "data/"
        file:      "data"
    """

    def _to_path(output):
        return (
            str(output) if not output.is_dir_checksum else os.path.join(str(output), "")
        )

    on_working_tree = isinstance(self.tree, LocalTree)

    def _to_checksum(output):
        if on_working_tree:
            return self.cache.local.tree.get_hash(output.path_info).value
        return output.checksum

    def _exists(output):
        if on_working_tree:
            return output.exists
        return True

    return {
        _to_path(output): _to_checksum(output)
        for stage in self.stages
        for output in stage.outs
        if _exists(output)
    }