fix: regression that replaces an unknown media type with */* (#4013)

src/PostgREST/MediaType.hs

@@ -155,7 +155,7 @@ decodeMediaType mt = decodeMediaType' $ decodeLatin1 mt
         mediaTypeOrError = P.parse tokenizeMediaType "parsec: tokenizeMediaType failed" $ T.unpack mt'
         (mainType, subType, params') = case mediaTypeOrError of
           Right mt'' -> mt''
-          Left _     -> ("*", "*", []) -- TODO: Throw mediatype error, would need refactoring because currently Error module depend on MediaType module
+          Left _     -> (mt',"",[])
         params = fromList $ map (first T.toLower) params' -- normalize parameter names to lowercase, per RFC 7321
         getPlan fmt = MTVndPlan mtFor fmt $
           [PlanAnalyze  | inOpts "analyze" ] ++

test/spec/Feature/Query/CustomMediaSpec.hs

@@ -375,3 +375,10 @@ spec = describe "custom media types" $ do
           { matchStatus  = 200
           , matchHeaders = ["Content-Type" <:> "application/octet-stream"]
           }
+
+  context "media type parser fails" $ do
+    it "sends media type as is" $
+      request methodGet "/items" (acceptHdrs "undefined") ""
+      `shouldRespondWith`
+      [json| {"code":"PGRST107","details":null,"hint":null,"message":"None of these media types are available: undefined"} |]
+      { matchStatus = 406 }