CLI exits with code 1 without an error message if directory is listed as output instead of file

### Which packages are impacted by your issue?

@graphql-codegen/cli

### Describe the bug

If you accidentally specify a directory instead of a filepath as a key in `generates`, the `graphql-codegen` command will exit with an error code of 1, but provide no other messaging as to what's gone wrong.

### Your Example Website or App

https://stackblitz.com/edit/github-itj2kj?file=package.json

### Steps to Reproduce the Bug or Issue

In the StackBlitz example terminal, run: `npm run codegen && echo done`

Notice that "done" is not printed; this is because the `codegen` step exits with code 1.

If you change `output` to `"output/types.ts"` in the `codegen.ts` file and run the same command, you'll see that the operation completes and prints out "done".

### Expected behavior

As a user, I expected some sort of error message to indicate what I've done wrong here, but instead an exit code (and a lack of generated output) is my only indication that anything's gone wrong at all.

### Screenshots or Videos

_No response_

### Platform

- OS: macOS 12.6.3
- NodeJS: v14.21.3 (but StackBlitz is on v16.14.2)
- `graphql` version: v16.6.0
- `@graphql-codegen/*` version(s):
- @graphql-codegen/cli@3.3.0
- @graphql-codegen/core@3.1.0
- @graphql-codegen/introspection@3.0.1
- @graphql-codegen/plugin-helpers@4.2.0
- @graphql-codegen/schema-ast@3.0.1
- @graphql-codegen/typescript-operations@3.0.3
- @graphql-codegen/typescript-resolvers@3.2.0
- @graphql-codegen/typescript@3.0.3
- @graphql-codegen/visitor-plugin-common@3.1.0

### Codegen Config File

```
import { CodegenConfig } from '@graphql-codegen/cli';

const config: CodegenConfig = {
schema: 'schema.graphql',
documents: 'document.graphql',
generates: {
// "output" is a directory
output: { plugins: ['typescript', 'typescript-operations'] },
},
};

export default config;
```

### Additional context

From stepping through the CLI code, it looks like there's just no error reporting on the output step.