fix(Google Drive Node): Continue on error support for download file operation

[RomanDavydchuk]

Summary

V2 of Google Drive node for some reason didn't properly handle this.continueOnFail() if the operation is download and resource is file. It was like this since the original overhaul PR, so it is not clear why it was done this way. But it means that if the node errors when downloading a file and continue on error is enabled - the node outputs nothing. This PR fixes that and makes sure that all operations are handled on error

Related Linear tickets, Github issues, and Community forum posts

https://linear.app/n8n/issue/NODE-4712/community-issue-google-drive-download-file-node-doesnt-continue-on
Closes #27312

Review / Merge checklist

• PR title and summary are descriptive. (conventions)
• Docs updated or follow-up ticket created.
• Tests included.
• PR Labeled with Backport to Beta, Backport to Stable, or Backport to v1 (if the PR is an urgent fix that needs to be backported)

[codecov]

Codecov Report

❌ Patch coverage is 33.33333% with 2 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...nodes-base/nodes/Google/Drive/v2/actions/router.ts	33.33%	2 Missing ⚠️

📢 Thoughts on this report? Let us know!

[cubic-dev-ai]

No issues found across 3 files

Architecture diagram

sequenceDiagram
    participant Engine as Workflow Engine
    participant Router as Google Drive Node (Router)
    participant API as Google Drive API

    Note over Engine, API: Loop for each input item

    Engine->>Router: execute(item)
    Router->>API: Request File Download (v3)

    alt Success Path
        API-->>Router: 200 OK (File Stream)
        Router->>Router: Process binary data
        Router-->>Engine: INodeExecutionData (Binary)
    else Error Path (e.g., 404 File Not Found)
        API-->>Router: Error Response
        Router->>Router: catch(error)

        alt NEW: continueOnFail() is ENABLED
            Router->>Router: CHANGED: Push error message to returnData
            Note right of Router: This ensures the node outputs<br/>the error JSON instead of nothing.
            Router-->>Engine: INodeExecutionData (JSON with error)
        else continueOnFail() is DISABLED
            Router-->>Engine: throw NodeOperationError
            Note right of Engine: Workflow stops (standard behavior)
        end
    end

    Note over Router, API: Next item or finish execution

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