[LyX/master] Fix compiler warning -Wstring-plus-int

[Scott Kostyshak]

commit 09e25ca5b7378271cdd361b572eeac680aa62d3d
Author: Scott Kostyshak <skostysh at lyx.org>
Date:   Thu Dec 29 16:25:42 2022 -0500

    Fix compiler warning -Wstring-plus-int
    
    Similar to d44eaa97.
---
 src/tex2lyx/math.cpp |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/src/tex2lyx/math.cpp b/src/tex2lyx/math.cpp
index 0e34798..616b616 100644
--- a/src/tex2lyx/math.cpp
+++ b/src/tex2lyx/math.cpp
@@ -92,7 +92,7 @@ void parse_math(Parser & p, ostream & os, unsigned flags, const mode_type mode)
 			}
 
 			else {
-				warning_message("\nmode: " + mode);
+				warning_message("\nmode: " + std::to_string(mode));
 				p.error("something strange in the parser\n");
 				break;
 			}