improve error message when creating a DictConfig from a bad dataclass

[omry]

Closes #697
Closes #658

This is not really fixing it completely, but the error message is more helpful.
It does indicate the offending type. and the key inside it instead of the full key in the config object. (providing the full key will be handled as a part of #514.

[jieru-hu]

Could you paste what the new error message looks like?

[omry]

from dataclasses import dataclass

from omegaconf import OmegaConf


@dataclass
class ConnectConf:
    # The root cause is the equals sign in ``default=``
    api_key: str = "${oc.env:API_KEY, default=abc123}"


@dataclass
class TasksConf:
    connect: ConnectConf = ConnectConf()


OmegaConf.structured(TasksConf)

Output:

Traceback (most recent call last):
....
omegaconf.errors.GrammarParseError: token recognition error at: '='
    full_key: api_key
    object_type=ConnectConf

[jieru-hu]

lgtm

[Jasha10]

Looks like a good improvement.
This does close #697, but I think that #658 is not resolved yet:

$ cat tmp658.py
from typing import Tuple
from dataclasses import dataclass
from omegaconf import OmegaConf

@dataclass
class TopLvlConf:
    foo: Tuple[str] = 123

OmegaConf.create(TopLvlConf)

$ python tmp658.py
Traceback (most recent call last):
...
omegaconf.errors.ValidationError: Invalid value assigned: int is not a ListConfig, list or tuple.
    full_key:
    object_type=None

[Jasha10]

I am working on a diff that will close #658.

[Jasha10]

I've pushed a commit to patch #658.

$ python tmp658.py
Traceback (most recent call last):
...
omegaconf.errors.ValidationError: Invalid value assigned: int is not a ListConfig, list or tuple.
    full_key: foo
    object_type=None

[omry]

Good catch Jasha, and thanks for the patch.