Add error handling for missing contact channel in verification (#704)

…andler

- Introduced `StatusError` to handle cases where the contact channel is
not found during email verification.
- Updated the verification code handler to check for the existence of
the contact channel before attempting to update its verification status,
improving robustness and user feedback.

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> [!IMPORTANT]
> Add error handling for missing contact channels in email verification
by introducing `StatusError` in `verification-code-handler.tsx`.
> 
>   - **Error Handling**:
> - Introduced `StatusError` in `verification-code-handler.tsx` to
handle missing contact channels during email verification.
> - Checks for contact channel existence before updating verification
status.
>   - **Behavior**:
> - Throws `StatusError` with message "Contact channel not found. Was
your contact channel deleted?" if contact channel is missing.
> 
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---------

Co-authored-by: Konsti Wohlwend <n2d4xc@gmail.com>
Co-authored-by: ellipsis-dev[bot] <65095814+ellipsis-dev[bot]@users.noreply.github.com>

apps/backend/src/app/api/latest/contact-channels/verify/verification-code-handler.tsx

@@ -60,7 +60,7 @@ export const contactChannelVerificationCodeHandler = createVerificationCodeHandl
 
     // This happens if the email is sent but then before the user clicks the link, the contact channel is deleted.
     if (!contactChannel) {
-      throw new StatusError(404, "Contact channel not found. Did you maybe delete your contact channel?");
+      throw new StatusError(400, "Contact channel not found. Was your contact channel deleted?");
     }
 
     await prismaClient.contactChannel.update({