fix syntax regressions (#1198, #1164)

src/forms.rs

@@ -384,8 +384,8 @@ pub(crate) fn fetch_atom_op_spec(
     spec: Option<OpDesc>,
     op_dir: &OpDir,
 ) -> Option<OpDesc> {
-    fetch_op_spec_from_existing(name, 1, spec, op_dir)
-        .or_else(|| fetch_op_spec_from_existing(name, 2, spec, op_dir))
+    fetch_op_spec_from_existing(name, 2, spec, op_dir)
+        .or_else(|| fetch_op_spec_from_existing(name, 1, spec, op_dir))
 }
 
 pub(crate) fn fetch_op_spec_from_existing(
@@ -430,6 +430,9 @@ pub(crate) fn fetch_op_spec(name: Atom, arity: usize, op_dir: &OpDir) -> Option<
                 }
             })
         }
+        0 => {
+            fetch_atom_op_spec(name, None, op_dir)
+        }
         _ => None,
     }
 }