From 7befd60c01c1593dd2db86fd4c695c3e9f26416e Mon Sep 17 00:00:00 2001
From: Tom Bereknyei <tomberek@gmail.com>
Date: Sun, 18 Aug 2024 22:35:54 -0400
Subject: [PATCH] fix: check to see if there are any lines before

(cherry picked from commit 59db8fd62b5300afbbabb1e8a12d547b336a3bdf)
---
 src/nix-build/nix-build.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/nix-build/nix-build.cc b/src/nix-build/nix-build.cc
index 0ce987d8a..a5b9e1e54 100644
--- a/src/nix-build/nix-build.cc
+++ b/src/nix-build/nix-build.cc
@@ -163,7 +163,7 @@ static void main_nix_build(int argc, char * * argv)
         script = argv[1];
         try {
             auto lines = tokenizeString<Strings>(readFile(script), "\n");
-            if (std::regex_search(lines.front(), std::regex("^#!"))) {
+            if (!lines.empty() && std::regex_search(lines.front(), std::regex("^#!"))) {
                 lines.pop_front();
                 inShebang = true;
                 for (int i = 2; i < argc; ++i)