From 4cd864236218bc974551586c46bea5b3a766859e Mon Sep 17 00:00:00 2001
From: Stefan Frederik <stefan.schippers@gmail.com>
Date: Mon, 6 Dec 2021 02:00:58 +0100
Subject: [PATCH] handle error conditions in tclget*var() functions

---
 src/scheduler.c | 32 ++++++++++++++++++++++++++++----
 1 file changed, 28 insertions(+), 4 deletions(-)

diff --git a/src/scheduler.c b/src/scheduler.c
index 92adc49c..fb907027 100644
--- a/src/scheduler.c
+++ b/src/scheduler.c
@@ -2734,22 +2734,46 @@ int xschem(ClientData clientdata, Tcl_Interp *interp, int argc, const char * arg
 
 double tclgetdoublevar(const char *s)
 {
-  return atof(Tcl_GetVar(interp,s, TCL_GLOBAL_ONLY));
+  const char *p;
+  p = Tcl_GetVar(interp, s, TCL_GLOBAL_ONLY | TCL_LEAVE_ERR_MSG);
+  if(!p) {
+    dbg(0, "%s\n", tclresult());
+    return 0.0;
+  }
+  return atof(p);
 }
 
 int tclgetintvar(const char *s)
 {
-  return atoi(Tcl_GetVar(interp,s, TCL_GLOBAL_ONLY));
+  const char *p;
+  p = Tcl_GetVar(interp, s, TCL_GLOBAL_ONLY | TCL_LEAVE_ERR_MSG);
+  if(!p) {
+    dbg(0, "%s\n", tclresult());
+    return 0;
+  }
+  return atoi(p);
 }
 
 int tclgetboolvar(const char *s)
 {
-  return Tcl_GetVar(interp,s, TCL_GLOBAL_ONLY)[0] == '1' ? 1 : 0;
+  const char *p;
+  p = Tcl_GetVar(interp, s, TCL_GLOBAL_ONLY | TCL_LEAVE_ERR_MSG);
+  if(!p) {
+    dbg(0, "%s\n", tclresult());
+    return 0;
+  }
+  return p[0] == '1' ? 1 : 0;
 }
 
 const char *tclgetvar(const char *s)
 {
-  return Tcl_GetVar(interp,s, TCL_GLOBAL_ONLY);
+  const char *p;
+  p = Tcl_GetVar(interp, s, TCL_GLOBAL_ONLY | TCL_LEAVE_ERR_MSG);
+  if(!p) {
+    dbg(0, "%s\n", tclresult());
+    return "";
+  }
+  return p;
 }
 
 const char *tcleval(const char str[])