repl.Stop() to only if running, fixes panic after js> exit followed by interrupt

ethereum/repl.go

@@ -23,6 +23,8 @@ type JSRepl struct {
 	prompt string
 
 	history *os.File
+
+	running bool
 }
 
 func NewJSRepl(ethereum *eth.Ethereum) *JSRepl {
@@ -35,6 +37,8 @@ func NewJSRepl(ethereum *eth.Ethereum) *JSRepl {
 }
 
 func (self *JSRepl) Start() {
+	if !self.running {
+		self.running = true
 		logger.Infoln("init JS Console")
 		reader := bufio.NewReader(self.history)
 		for {
@@ -50,12 +54,16 @@ func (self *JSRepl) Start() {
 		}
 		self.read()
 	}
+}
 
 func (self *JSRepl) Stop() {
+	if self.running {
+		self.running = false
 		self.re.Stop()
 		logger.Infoln("exit JS Console")
 		self.history.Close()
 	}
+}
 
 func (self *JSRepl) parseInput(code string) {
 	defer func() {