[Google Drive Node] Improve error message when folder ID is provided instead of file ID

[N1ghtmarecus]

Summary

When attempting to download a file from Google Drive, if the user mistakenly provided a folder ID instead of a file ID, the node was returning a generic:
403 Forbidden – check your credentials

This was misleading because the issue was not related to authentication/credentials, but to the wrong type of resource (folder instead of file).

This PR adds an explicit check for mimeType === folder, and throws a clear, actionable error message:
The provided ID refers to a folder. Please provide a file ID to download.

This way, users immediately understand the root cause and how to fix it.

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How to test

1. Use the Google Drive node → Download operation.
2. Provide a folder ID instead of a file ID.
3. Before: misleading 403 Forbidden – check your credentials.
   After: clear error message about using a folder ID.

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[cubic-dev-ai]

No issues found across 1 file

[Joffcom]

Hey @N1ghtmarecus,

Thank you for your contribution. We appreciate the time and effort you’ve taken to submit this pull request.

Before we can proceed, please ensure the following:
• Tests are included for any new functionality, logic changes or bug fixes.
• The PR aligns with our contribution guidelines.

Regarding new nodes:
We no longer accept new nodes directly into the core codebase. Instead, we encourage contributors to follow our Community Node Submission Guide to publish nodes independently.

If your node integrates with an AI service that you own or represent, please email nodes@n8n.io and we will be happy to discuss the best approach.

About review timelines:
This PR has been added to our internal tracker as "GHC-4132". While we plan to review it, we are currently unable to provide an exact timeframe. Our goal is to begin reviews within a month, but this may change depending on team priorities. We will reach out when the review begins.

Thank you again for contributing to n8n.