Bug: Chatwoot → Cloud API audio fails with `TypeError: t.mimetype?.startsWith is not a function

[victorexcom]

📋 Bug Description

Environment

• Evolution API: v2.3.7
• Chatwoot: latest
• Integration: WhatsApp Business Cloud API
• Storage: IDrive E2 (S3 compatible)
• Docker deployment

Problem

Sending an audio attachment from Chatwoot to a WhatsApp Cloud API instance fails with:

TypeError: t.mimetype?.startsWith is not a function
    at Ls.audioWhatsapp
    at ut.sendAttachment
    at ut.receiveWebhook

Text messages, images and PDFs are sent successfully. Only audio attachments are affected.

Reproduction

1. Configure Chatwoot with Evolution API.
2. Configure a WhatsApp Business Cloud API instance.
3. Open a conversation.
4. Send an audio message from the Chatwoot interface.
5. The request fails before reaching Meta.

Comparison

Scenario A — audio sent directly using the Evolution API endpoint
Result: ✅ No mimetype?.startsWith exception. Evolution continues processing normally.

Scenario B — the exact same audio sent from Chatwoot
Result: ❌ Exception thrown immediately, before the request reaches Meta:

TypeError: t.mimetype?.startsWith is not a function

Payload comparison (anonymized)

Works — direct Evolution API call:

{
  "mimetype": "audio/ogg"
  // ...
}

Fails — via Chatwoot:

{
  "mimetype": null
  // or {}, or the actual captured value — TO FILL IN
}

(placeholder — replace with the real captured object once logged; see note below)

Expected behavior

Evolution should correctly detect or normalize the attachment MIME type received from Chatwoot before calling audioWhatsapp(). Since ?. only guards against null/undefined, a non-null, non-string mimetype (object, array, etc.) reaches .startsWith() unguarded and throws.

Additional information

This appears to affect only the Chatwoot → Cloud API attachment flow. The direct Evolution API → Cloud API flow works correctly.

If necessary, I can provide the complete stack trace, the Chatwoot payload, the Evolution payload, and a full comparison between both requests.

🔄 Steps to Reproduce

1. Configure Chatwoot with Evolution API.
2. Configure a WhatsApp Business Cloud API instance.
3. Open a conversation in Chatwoot.
4. Send an audio message from the Chatwoot interface.
5. Request fails with TypeError before reaching Meta:
   TypeError: t.mimetype?.startsWith is not a function
   at Ls.audioWhatsapp
   at ut.sendAttachment
   at ut.receiveWebhook

Note: sending the same audio directly via the Evolution API endpoint (bypassing Chatwoot) works fine — no exception.

✅ Expected Behavior

Evolution should correctly detect or normalize the attachment MIME type received from Chatwoot before calling audioWhatsapp()

❌ Actual Behavior

TypeError: t.mimetype?.startsWith is not a function
at Ls.audioWhatsapp
at ut.sendAttachment
at ut.receiveWebhook

🌍 Environment

• OS: [e.g. Ubuntu 20.04, Windows 10, macOS 12.0]
• Node.js version: [e.g. 18.17.0]
• Evolution API version: [e.g. 2.3.7]
• Database: [e.g. PostgreSQL 14, MySQL 8.0]
• Connection type: [e.g. Baileys, WhatsApp Business API]

📋 Logs

📝 Additional Context

No response