Precedence of response codes

Consider, for example the request:

PUT /test-put-bc/dahut-bc.ttl
Authorization: Bearer SoOP3RS1krIT
If-None-Match: *
User-Agent: libwww-perl/6.36
Content-Type: text/turtle
Link: <http://www.w3.org/ns/ldp#BasicContainer>; rel="type"

@prefix dc: <http://purl.org/dc/terms/>.
<> dc:title "Container Interaction Model"@en .

If the resource already exists, there are two different reasons why this request should fail:

• It should fail with a 409 because ldp:BasicContainer is inconsistent with that the request URI does not end with a /.
• It should fail with a 412 because it failed the precondition set by the If-None-Match: * header.

In such cases, should we express what should be checked first, IOW, what error message the client should see in every case, or should we leave that up to implementations?