patch 9.0.1935: Vim9: not consistent error messages

Problem:  Vim9: not consistent error messages
Solution: Make error messages more consistent. Use "variable" for
          (object/class) member

closes: #13155

Signed-off-by: Christian Brabandt <cb@256bit.org>
Co-authored-by: RestorerZ <restorer@mail2k.ru>
diff --git a/src/vim9compile.c b/src/vim9compile.c
index c69afb9..269d801 100644
--- a/src/vim9compile.c
+++ b/src/vim9compile.c
@@ -1610,8 +1610,8 @@
 	     || (!is_object && cctx->ctx_ufunc->uf_class != cl)))
     {
 	char *msg = (m->ocm_access == VIM_ACCESS_PRIVATE)
-				? e_cannot_access_private_member_str
-				: e_member_is_not_writable_str;
+				? e_cannot_access_private_variable_str
+				: e_variable_is_not_writable_str;
 	semsg(_(msg), m->ocm_name, cl->class_name);
 	return FALSE;
     }
@@ -1750,7 +1750,7 @@
 		{
 		    // A class variable can be accessed without the class name
 		    // only inside a class.
-		    semsg(_(e_class_member_str_accessible_only_inside_class_str),
+		    semsg(_(e_class_variable_str_accessible_only_inside_class_str),
 			    lhs->lhs_name, defcl->class_name);
 		    return FAIL;
 		}