From bb34e22f31996924f5d12a49983bc2ee2a502284 Mon Sep 17 00:00:00 2001
From: dev-gto <43351700+dev-gto@users.noreply.github.com>
Date: Fri, 20 Mar 2026 09:38:03 -0300
Subject: [PATCH] Fix index out of range

A mal-formed PDF can lead to an unexpected runtime error: index out of range [-1]
---
 page.go | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/page.go b/page.go
index 479b243..322a43a 100644
--- a/page.go
+++ b/page.go
@@ -496,8 +496,10 @@ func (p Page) Content() (result Content) {
 
 		case "Q": // restore graphics state
 			n := len(gstack) - 1
-			g = gstack[n]
-			gstack = gstack[:n]
+			if n >= 0 {
+			    g = gstack[n]
+			    gstack = gstack[:n]
+			}
 
 		case "BT": // begin text (reset text matrix and line matrix)
 			g.Tm = ident