##### SUMMARY
The delete operation of the `lightsail` module is not idempotent. If the instance is already deleted, then the task generates a traceback.

```
Traceback (most recent call last):
  File "ansible/modules/cloud/amazon/lightsail.py", line 458, in main
  File "ansible/modules/cloud/amazon/lightsail.py", line 422, in core
  File "ansible/module_utils/common/dict_transformations.py", line 42, in camel_dict_to_snake_dict
    for k, v in camel_dict.items():
AttributeError: 'NoneType' object has no attribute 'items'
```

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
`lightsail`

##### ANSIBLE VERSION
<!--- Paste verbatim output from "ansible --version" between quotes -->
```paste below
ansible 2.10.0.dev0
```

##### CONFIGURATION
<!--- Paste verbatim output from "ansible-config dump --only-changed" between quotes -->
```paste below
nothing
```

##### OS / ENVIRONMENT
<!--- Provide all relevant information below, e.g. target OS versions, network device firmware, etc. -->
Python 3.7.4

##### STEPS TO REPRODUCE
<!--- Describe exactly how to reproduce the problem, using a minimal test-case -->

<!--- Paste example playbooks or commands between quotes below -->
```yaml
- lightsail:
    state: absent
    name: my_instance
```

##### EXPECTED RESULTS
<!--- Describe what you expected to happen when running the steps above -->
Task successfully returns with `changed: false`.

##### ACTUAL RESULTS
<!--- Describe what actually happened. If possible run with extra verbosity (-vvvv) -->
Instead this traceback is generated - 
<!--- Paste verbatim command output between quotes -->
```paste below
Traceback (most recent call last):
  File "ansible/modules/cloud/amazon/lightsail.py", line 458, in main
  File "ansible/modules/cloud/amazon/lightsail.py", line 422, in core
  File "ansible/module_utils/common/dict_transformations.py", line 42, in camel_dict_to_snake_dict
    for k, v in camel_dict.items():
AttributeError: 'NoneType' object has no attribute 'items'

```

common_name: ""
          from_port: 22
          protocol: tcp
          to_port: 22
    private_ip_address: "172.26.8.14"
    public_ip_address: "34.207.152.202"
    resource_type: "Instance"
    ssh_key_name: "keypair"
    state:
      code: 16
      name: running
    support_code: "588307843083/i-0997c97831ee21e33"
    username: "ubuntu"
'''
import time
import traceback
try:
    import botocore
    HAS_BOTOCORE = True
except ImportError:
    HAS_BOTOCORE = False
try:
    import boto3
except ImportError:
    
    pass
from ansible.module_utils.basic import AnsibleModule
from ansible.module_utils.ec2 import (ec2_argument_spec, get_aws_connection_info, boto3_conn,
                                      HAS_BOTO3, camel_dict_to_snake_dict)
def create_instance(module, client, instance_name):