fix(Blockchain): handle closed BlockStore when initializing

Fixes errors in the Blockchain tests.

lib/blockchain.js

@@ -15,6 +15,7 @@ if (process.browser) {
 function noop () {}
 
 var TIME_MARGIN = 2 * 60 * 60
+var storeClosedError = new Error('Store is closed')
 
 var Blockchain = module.exports = function (opts) {
   var self = this
@@ -40,7 +41,8 @@ var Blockchain = module.exports = function (opts) {
 
   this.store = opts.store || new BlockStore({ path: opts.path })
   this._initStore(function (err) {
-    if (err) return self._error(err)
+    if (err && err !== storeClosedError) return self._error(err)
+    else if (err && err === storeClosedError) return
     self.initialized = true
     self.emit('ready')
   })
@@ -68,7 +70,7 @@ Blockchain.prototype._initStore = function (cb) {
     return function (cb) {
       self.store.get(block.hash, function (err) {
         if (err && !err.notFound) return cb(err)
-        if (self.closed || self.store.isClosed()) return cb(new Error('Store is closed'))
+        if (self.closed || self.store.isClosed()) return cb(storeClosedError)
         self.store.put(block, cb)
       })
     }