From: InSync <122007197+InSyncWithFoo@users.noreply.github.com>
Date: Sat, 13 Jan 2024 05:04:57 +0000
Subject: [PATCH] Avoid assigning an empty error message to delegated parse
 exception


diff --git a/pyparsing/core.py b/pyparsing/core.py
index 73514ed..fc19d1c 100644
--- a/pyparsing/core.py
+++ b/pyparsing/core.py
@@ -4569,7 +4569,8 @@ class ParseElementEnhance(ParserElement):
                 return self.expr._parse(instring, loc, doActions, callPreParse=False)
             except ParseBaseException as pbe:
                 if not isinstance(self, Forward) or self.customName is not None:
-                    pbe.msg = self.errmsg
+                    if self.errmsg:
+                        pbe.msg = self.errmsg
                 raise
         else:
             raise ParseException(instring, loc, "No expression defined", self)