fix(gnovm): handle case of NumStmts = 0 when creating stacktraces

gno.land/cmd/gnoland/testdata/issue_outofgas_stacktrace.txtar

@@ -0,0 +1,40 @@
+# test for a bug involving printing stacktraces with missing statements;
+# when dumping out information for a test.
+# more info: https://github.com/gnolang/gno/pull/2813
+
+loadpkg gno.land/p/demo/avl
+gnoland start
+
+! gnokey maketx addpkg -pkgdir $WORK -pkgpath gno.land/r/pkg1 -gas-fee 1000000ugnot -gas-wanted 10000000 -broadcast -chainid=tendermint_test test1
+
+stderr 'out of gas'
+
+
+-- pkg1.gno --
+package hello
+
+import (
+	"strconv"
+
+	"gno.land/p/demo/avl"
+)
+
+var hello avl.Tree
+
+var helloMap = make(map[string]string)
+
+func init() {
+	for i := 0; i < 1000; i++ {
+		s := strconv.Itoa(i)
+		hello.Set(s, "123")
+		helloMap[s] = "123"
+	}
+}
+
+func Render(s string) string {
+	if s == "map" {
+		return helloMap["100"]
+	}
+	res, _ := hello.Get("100")
+	return res.(string)
+}

gnovm/pkg/gnolang/frame.go

@@ -125,7 +125,11 @@ func (s Stacktrace) String() string {
 			fmt.Fprintf(&builder, "    gonative:%s.%s\n", call.Frame.Func.NativePkg, call.Frame.Func.NativeName)
 		case call.Frame.Func != nil:
 			fmt.Fprintf(&builder, "%s\n", toExprTrace(cx))
-			fmt.Fprintf(&builder, "    %s/%s:%d\n", call.Frame.Func.PkgPath, call.Frame.Func.FileName, call.Stmt.GetLine())
+			line := 0
+			if call.Stmt != nil {
+				line = call.Stmt.GetLine()
+			}
+			fmt.Fprintf(&builder, "    %s/%s:%d\n", call.Frame.Func.PkgPath, call.Frame.Func.FileName, line)
 		case call.Frame.GoFunc != nil:
 			fmt.Fprintf(&builder, "%s\n", toExprTrace(cx))
 			fmt.Fprintf(&builder, "    gofunction:%s\n", call.Frame.GoFunc.Value.Type())

gnovm/pkg/gnolang/machine.go

@@ -480,9 +480,12 @@ func (m *Machine) Stacktrace() (stacktrace Stacktrace) {
 	nextStmtIndex := len(m.Stmts) - 1
 	for i := len(m.Frames) - 1; i >= 0; i-- {
 		if m.Frames[i].IsCall() {
-			stm := m.Stmts[nextStmtIndex]
-			bs := stm.(*bodyStmt)
-			stm = bs.Body[bs.NextBodyIndex-1]
+			var stm Stmt
+			if nextStmtIndex >= 0 {
+				stm = m.Stmts[nextStmtIndex]
+				bs := stm.(*bodyStmt)
+				stm = bs.Body[bs.NextBodyIndex-1]
+			}
 			calls = append(calls, StacktraceCall{
 				Stmt:  stm,
 				Frame: m.Frames[i],