chore: guard against inherited properties

lib/createClient.js

@@ -42,6 +42,9 @@ module.exports = function createClient (portArg, hostArg, options) {
       if (parsed.search !== '') {
         var elem
         for (elem in parsed.query) {
+          if (!parsed.query.hasOwnProperty(elem)) {
+            continue
+          }
           // If options are passed twice, only the parsed options will be used
           if (elem in options) {
             if (options[elem] === parsed.query[elem]) {

lib/extendedApi.js

@@ -85,7 +85,9 @@ RedisClient.prototype.duplicate = function (options, callback) {
   const existingOptions = utils.clone(this.options)
   options = utils.clone(options)
   for (const elem in options) {
-    existingOptions[elem] = options[elem]
+    if (options.hasOwnProperty(elem)) {
+      existingOptions[elem] = options[elem]
+    }
   }
   const client = new RedisClient(existingOptions)
   client.selectedDb = this.selectedDb

lib/readyHandler.js

@@ -72,13 +72,15 @@ function onReady (client) {
   if (!client.options.disableResubscribing && callbackCount) {
     debug('Sending pub/sub onReady commands')
     for (const key in client.subscriptionSet) {
-      const command = key.slice(0, key.indexOf('_'))
-      const args = client.subscriptionSet[key]
-      client[command]([args]).catch((err) => {
-        if (!client.closing) {
-          process.nextTick(() => client.emit('error', err))
-        }
-      })
+      if (client.subscriptionSet.hasOwnProperty(key)) {
+        const command = key.slice(0, key.indexOf('_'))
+        const args = client.subscriptionSet[key]
+        client[command]([args]).catch((err) => {
+          if (!client.closing) {
+            process.nextTick(() => client.emit('error', err))
+          }
+        })
+      }
     }
   }
   client.sendOfflineQueue()