az managedapp show --name crash

## Describe the bug

**Command Name**
`az managedapp show`

**Errors:**
```
The command failed with an unexpected error. Here is the traceback:
No value for given attribute
Traceback (most recent call last):
File "/opt/az/lib/python3.6/site-packages/knack/cli.py", line 231, in invoke
cmd_result = self.invocation.execute(args)
File "/opt/az/lib/python3.6/site-packages/azure/cli/core/commands/__init__.py", line 657, in execute
raise ex
File "/opt/az/lib/python3.6/site-packages/azure/cli/core/commands/__init__.py", line 720, in _run_jobs_serially
results.append(self._run_job(expanded_arg, cmd_copy))
File "/opt/az/lib/python3.6/site-packages/azure/cli/core/commands/__init__.py", line 691, in _run_job
result = cmd_copy(params)
File "/opt/az/lib/python3.6/site-packages/azure/cli/core/commands/__init__.py", line 328, in __call__
return self.handler(*args, **kwargs)
File "/opt/az/lib/python3.6/site-packages/azure/cli/core/commands/command_operation.py", line 363, in handler
show_exception_handler(ex)
File "/opt/az/lib/python3.6/site-packages/azure/cli/core/commands/arm.py", line 417, in show_exception_handler
raise ex
File "/opt/az/lib/python3.6/site-packages/azure/cli/core/commands/command_operation.py", line 361, in handler
return op(**command_args)
File "/opt/az/lib/python3.6/site-packages/azure/cli/command_modules/resource/custom.py", line 1356, in show_application
return racf.applications.get(resource_group_name, application_name)
File "/opt/az/lib/python3.6/site-packages/azure/mgmt/resource/managedapplications/operations/_applications_operations.py", line 79, in get
'resourceGroupName': self._serialize.url("resource_group_name", resource_group_name, 'str', max_length=90, min_length=1, pattern=r'^[-\w\._\(\)]+$'),
File "/opt/az/lib/python3.6/site-packages/msrest/serialization.py", line 650, in url
output = self.serialize_data(data, data_type, **kwargs)
File "/opt/az/lib/python3.6/site-packages/msrest/serialization.py", line 758, in serialize_data
raise ValueError("No value for given attribute")
ValueError: No value for given attribute

```

## To Reproduce:
Steps to reproduce the behavior. Note that argument values have been redacted, as they may contain sensitive information.

- `az managedapp show --name `

## Expected Behavior
Correct command output or report of failure, no crash

## Environment Summary
```
Linux-5.4.0-1051-azure-x86_64-with-debian-buster-sid
Python 3.6.10
Installer: DEB

azure-cli 2.25.0

```
## Additional Context