chore: check we have fields in our Logical Model before outputting a parser

PR-URL: https://github.com/hasura/graphql-engine-mono/pull/10550
GitOrigin-RevId: 85f83274f696e381da68547bf7af098ea8f5ac11

server/src-lib/Hasura/LogicalModel/Schema.hs

@@ -250,13 +250,22 @@ defaultLogicalModelSelectionSet logicalModel = runMaybeT do
       -- We entirely ignore Relay for now.
       implementsInterfaces = mempty
 
-  lift $ P.memoizeOn 'defaultLogicalModelSelectionSet fieldName do
-    -- we filter out parsers that return 'Nothing' as those we are no permitted to see.
-    parsers <- catMaybes <$> traverse (\(column, lmField, redactionExp) -> parseLogicalModelField mempty column lmField redactionExp) allowedColumns
+  -- we filter out parsers that return 'Nothing' as those we are no permitted to see.
+  parsers <-
+    catMaybes
+      <$> traverse
+        ( \(column, lmField, redactionExp) ->
+            lift (parseLogicalModelField mempty column lmField redactionExp)
+        )
+        allowedColumns
 
-    pure
-      $ P.selectionSetObject fieldName description parsers implementsInterfaces
-      <&> parsedSelectionsToFields IR.AFExpression
+  -- if we have no fields, we can't create a parser
+  if null parsers
+    then hoistMaybe Nothing
+    else lift $ P.memoizeOn 'defaultLogicalModelSelectionSet fieldName do
+      pure
+        $ P.selectionSetObject fieldName description parsers implementsInterfaces
+        <&> parsedSelectionsToFields IR.AFExpression
 
 logicalModelSelectionList ::
   (MonadBuildSchema b r m n, BackendLogicalModelSelectSchema b) =>