override auth fails in empty projects: Cannot convert undefined or null to object

### Before opening, please confirm:

- [X] I have installed the latest version of the Amplify CLI (see above), and confirmed that the issue still persists.
- [X] I have [searched for duplicate or closed issues](https://github.com/aws-amplify/amplify-cli/issues?q=is%3Aissue+).
- [X] I have read the guide for [submitting bug reports](https://github.com/aws-amplify/amplify-cli/blob/master/CONTRIBUTING.md#bug-reports).
- [X] I have done my best to include a minimal, self-contained set of instructions for consistently reproducing the issue.

### How did you install the Amplify CLI?

npm

### If applicable, what version of Node.js are you using?

14

### Amplify CLI Version

7.x

### What operating system are you using?

macos

### Amplify Categories

auth

### Amplify Commands

Not applicable

### Describe the bug

`override auth` fails when project has no resources:

```
Cannot convert undefined or null to object
TypeError: Cannot convert undefined or null to object
at Function.keys ()
at Object.run (/Users/attila/workspaces/amplify-cli/packages/amplify-category-auth/lib/commands/auth/override.js:17:12)
at Object.executeAmplifyCommand (/Users/attila/workspaces/amplify-cli/packages/amplify-category-auth/lib/index.js:336:25)
at /Users/attila/workspaces/amplify-cli/packages/amplify-cli/lib/execution-manager.js:203:51
at executePluginModuleCommand (/Users/attila/workspaces/amplify-cli/packages/amplify-cli/lib/execution-manager.js:187:11)
at processTicksAndRejections (internal/process/task_queues.js:95:5)
at async Object.executeCommand (/Users/attila/workspaces/amplify-cli/packages/amplify-cli/lib/execution-manager.js:35:9)
at async Object.run (/Users/attila/workspaces/amplify-cli/packages/amplify-cli/lib/index.js:162:9)
```

### Expected behavior

Provide proper error message

### Reproduction steps

1. amplify init
2. amplify add override

### GraphQL schema(s)

```graphql
# Put schemas below this line

```

### Log output

```
# Put your logs below this line

```

### Additional information

_No response_