From 31a4915012b2ba84740bae2e11cea4ee2aeac191 Mon Sep 17 00:00:00 2001
From: Florian Foinant-Willig <FlachyJoe@users.noreply.github.com>
Date: Mon, 6 May 2024 18:06:27 +0200
Subject: [PATCH] Fix 12755 (#13802)

---
 src/Mod/Sketcher/Gui/DrawSketchHandlerArc.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/Mod/Sketcher/Gui/DrawSketchHandlerArc.h b/src/Mod/Sketcher/Gui/DrawSketchHandlerArc.h
index 20fd271ec8..b4ce06aa10 100644
--- a/src/Mod/Sketcher/Gui/DrawSketchHandlerArc.h
+++ b/src/Mod/Sketcher/Gui/DrawSketchHandlerArc.h
@@ -833,6 +833,12 @@ void DSHArcController::addConstraints()
         }
     }
     else {  // Valid diagnosis. Must check which constraints may be added.
+
+        // if no curve exists a crash occurs #12755
+        if (firstCurve < 0) {
+            return;
+        }
+
         auto startpointinfo = handler->getPointInfo(GeoElementId(firstCurve, pos1));
 
         if (x0set && startpointinfo.isXDoF()) {