Merge pull request #394 from OffchainLabs/flatcalltracer

backport #393 to nitro v3.3.x - fix flatCallTracer onexit out of bound

Author: joshuacolvin0

eth/tracers/api_test.go

@@ -1019,7 +1019,7 @@ func newTestMergedBackend(t *testing.T, n int, gspec *core.Genesis, generator fu
 		SnapshotLimit:     0,
 		TrieDirtyDisabled: true, // Archive mode
 	}
-	chain, err := core.NewBlockChain(backend.chaindb, cacheConfig, gspec, nil, backend.engine, vm.Config{}, nil, nil)
+	chain, err := core.NewBlockChain(backend.chaindb, cacheConfig, nil, gspec, nil, backend.engine, vm.Config{}, nil, nil)
 	if err != nil {
 		t.Fatalf("failed to create tester chain: %v", err)
 	}

eth/tracers/native/call_flat.go

@@ -195,6 +195,9 @@ func (t *flatCallTracer) OnExit(depth int, output []byte, gasUsed uint64, err er
 	if t.config.IncludePrecompiles {
 		return
 	}
+	if len(t.tracer.callstack[len(t.tracer.callstack)-1].Calls) == 0 {
+		return
+	}
 	var (
 		// call has been nested in parent
 		parent = t.tracer.callstack[len(t.tracer.callstack)-1]