internal/ethapi: fix trace log marshalling (#23292)

internal/ethapi/api.go

@@ -1120,7 +1120,7 @@ type StructLogRes struct {
 	Gas     uint64             `json:"gas"`
 	GasCost uint64             `json:"gasCost"`
 	Depth   int                `json:"depth"`
-	Error   error              `json:"error,omitempty"`
+	Error   string             `json:"error,omitempty"`
 	Stack   *[]string          `json:"stack,omitempty"`
 	Memory  *[]string          `json:"memory,omitempty"`
 	Storage *map[string]string `json:"storage,omitempty"`
@@ -1136,7 +1136,7 @@ func FormatLogs(logs []vm.StructLog) []StructLogRes {
 			Gas:     trace.Gas,
 			GasCost: trace.GasCost,
 			Depth:   trace.Depth,
-			Error:   trace.Err,
+			Error:   trace.ErrorString(),
 		}
 		if trace.Stack != nil {
 			stack := make([]string, len(trace.Stack))