### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

Dynamodb Batch write request throws 500 error when DYNAMODB_ERROR_PROBABILITY is set to >0

Stack trace below
```
2023-02-01T21:50:21.918 ERROR --- [   asgi_gw_4] l.aws.handlers.logging     : exception during call chain
2023-02-01 13:50:22 Traceback (most recent call last):
2023-02-01 13:50:22   File "/opt/code/localstack/localstack/aws/chain.py", line 90, in handle
2023-02-01 13:50:22     handler(self, self.context, response)
2023-02-01 13:50:22   File "/opt/code/localstack/localstack/aws/handlers/service.py", line 122, in __call__
2023-02-01 13:50:22     handler(chain, context, response)
2023-02-01 13:50:22   File "/opt/code/localstack/localstack/aws/handlers/service.py", line 92, in __call__
2023-02-01 13:50:22     skeleton_response = self.skeleton.invoke(context)
2023-02-01 13:50:22   File "/opt/code/localstack/localstack/aws/skeleton.py", line 153, in invoke
2023-02-01 13:50:22     return self.dispatch_request(context, instance)
2023-02-01 13:50:22   File "/opt/code/localstack/localstack/aws/skeleton.py", line 165, in dispatch_request
2023-02-01 13:50:22     result = handler(context, instance) or {}
2023-02-01 13:50:22   File "/opt/code/localstack/localstack/aws/forwarder.py", line 56, in _call
2023-02-01 13:50:22     return handler(context, req)
2023-02-01 13:50:22   File "/opt/code/localstack/localstack/aws/skeleton.py", line 117, in __call__
2023-02-01 13:50:22     return self.fn(*args, **kwargs)
2023-02-01 13:50:22   File "/opt/code/localstack/localstack/aws/api/core.py", line 151, in operation_marker
2023-02-01 13:50:22     return fn(*args, **kwargs)
2023-02-01 13:50:22   File "/opt/code/localstack/localstack/services/dynamodb/provider.py", line 860, in batch_write_item
2023-02-01 13:50:22     unprocessed_items[table_name].append({key: unprocessed_items[key]})
2023-02-01 13:50:22 KeyError: 'Snapshots'
2023-02-01 13:50:22 2023-02-01T21:50:21.919  INFO --- [   asgi_gw_4] localstack.request.aws     : AWS dynamodb.BatchWriteItem => 500 (InternalError)
```

### Expected Behavior

Not throwing 500 error. only 400 (ProvisionedThroughputExceededException) is expected.

### How are you starting LocalStack?

With a docker-compose file

### Steps To Reproduce

#### How are you starting localstack (e.g., `bin/localstack` command, arguments, or `docker-compose.yml`)

    docker run localstack/localstack
under environment set 

`DYNAMODB_ERROR_PROBABILITY=0.5`

Or with local stack cli
`DEBUG=1 DYNAMODB_ERROR_PROBABILITY=0.5 localstack start -d`

#### Client commands (e.g., AWS SDK code snippet, or sequence of "awslocal" commands)
through java client
dynamoDbClient.batchWriteItem(batchRequest)
I believe it's the same for any client.since it's 500 error

### Environment

```markdown
- OS:macos 13.2
- LocalStack: latest
```


### Anything else?

_No response_
import copy
import json
import logging
import os.path
import random
import re
import time
import traceback
from binascii import crc32
from contextlib import contextmanager
from typing import Dict, List
import requests
import werkzeug
from localstack import config
from localstack.aws import handlers
from localstack.aws.accounts import get_aws_account_id
from localstack.aws.api import (
    CommonServiceException,
    RequestContext,
    ServiceRequest,
    ServiceResponse,
    handler,