Bug 37963: Case 1 - Return if sushi_errors even if response code >= 400

Bug 37963: Case 1 - Return if sushi_errors even if response code >= 400

This ensures that SUSHI errors, if present, are shown on the UI even if
response->code >= 400.
This means that if, for example, SUSHI provider returns 401 with SUSHI
error like so:
{"Code": 2020, "Severity": "Error", "Message": "API Key Invalid"}

Then, the 'API Key Invalid' will be shown to the user, without having to
check logs.

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>