dataclass-wizard

To fix this, either define the 'your_unmapped_key' field in your dataclass, or configure the `JSONWizard.Meta` class to ignore unknown keys or capture them using a `CatchAll` field.

Example to ignore unknown keys:
```python
from dataclasses import dataclass
from dataclass_wizard import JSONWizard

@dataclass
class MyData(JSONWizard):
    class _(JSONWizard.Meta):
        raise_on_unknown_json_key = False # Default behavior, but can be explicitly set
    field_a: str
    field_b: int

# Or to capture them:
from dataclass_wizard.enums import CatchAll
@dataclass
class MyDataWithCatchAll(JSONWizard):
    field_a: str
    unknown_fields: CatchAll
```

This issue has been resolved in newer versions of `dataclass-wizard`. Upgrade the library to the latest version (0.32.1 or higher is mentioned as a fix for a related bug in 0.32.0, so generally upgrading is the solution).

```bash
pip install --upgrade dataclass-wizard
```

Enable the `recursive_classes` flag in the `Meta` configuration for your dataclass, or bind it using `LoadMeta`.

```python
from dataclasses import dataclass
from dataclass_wizard import JSONWizard, LoadMeta

@dataclass
class Node:
    name: str
    children: list['Node']

# Method 1: Using an inner Meta class
@dataclass
class MyTree(JSONWizard):
    class _(JSONWizard.Meta):
        recursive_classes = True
    root: Node

# Method 2: Using LoadMeta.bind_to
LoadMeta(recursive_classes=True).bind_to(Node)
```

Define a `tag_key` in the `JSONWizard.Meta` configuration and ensure your JSON input includes this tag to help `dataclass-wizard` determine the correct class for deserialization within the Union type.

```python
from dataclasses import dataclass
from typing import Union
from dataclass_wizard import JSONWizard

@dataclass
class Cat:
    name: str
    type: str = 'cat'

@dataclass
class Dog:
    name: str
    type: str = 'dog'

@dataclass
class PetContainer(JSONWizard):
    class _(JSONWizard.Meta):
        # 'type' field in the JSON will determine which class to use
        tag_key = 'type'
        auto_assign_tags = True # Automatically adds the 'type' field on serialization
    pet: Union[Cat, Dog]

# Example JSON: {'pet': {'type': 'cat', 'name': 'Whiskers'}}
```