Fix embeded relations error message (#767)

src/PostgREST/App.hs

@@ -315,10 +315,6 @@ contentRangeH lower upper total =
       totalNotZero  = fromMaybe True ((/=) 0 <$> total)
       fromInRange   = lower <= upper
 
-formatRelationError :: Text -> Text
-formatRelationError = formatGeneralError
-  "could not find foreign keys between these entities"
-
 formatParserError :: ParseError -> Text
 formatParserError e = formatGeneralError message details
   where
@@ -327,14 +323,15 @@ formatParserError e = formatGeneralError message details
        $ showErrorMessages "or" "unknown parse error" "expecting" "unexpected" "end of input" (errorMessages e)
 
 formatGeneralError :: Text -> Text -> Text
-formatGeneralError message details = toS $ encode $ object [
-  "message" .= message,
-  "details" .= details]
+formatGeneralError message details = message <> ", " <> details
 
 augumentRequestWithJoin :: Schema ->  [Relation] ->  ReadRequest -> Either Text ReadRequest
 augumentRequestWithJoin schema allRels request =
   (first formatRelationError . addRelations schema allRels Nothing) request
   >>= addJoinConditions schema
+  where
+    formatRelationError = formatGeneralError
+      "could not find foreign keys between these entities"
 
 addFiltersOrdersRanges :: ApiRequest -> Either ParseError (ReadRequest -> ReadRequest)
 addFiltersOrdersRanges apiRequest = foldr1 (liftA2 (.)) [