diff --git a/app/command_channel_header.go b/app/command_channel_header.go
index db92f68b2d..c63787ee76 100644
--- a/app/command_channel_header.go
+++ b/app/command_channel_header.go
@@ -62,7 +62,8 @@ func (me *HeaderProvider) DoCommand(a *App, args *model.CommandArgs, message str
 
 	case model.CHANNEL_GROUP, model.CHANNEL_DIRECT:
 		// Modifying the header is not linked to any specific permission for group/dm channels, so just check for membership.
-		channelMember, err := a.GetChannelMember(args.ChannelId, args.Session.UserId)
+		var channelMember *model.ChannelMember
+		channelMember, err = a.GetChannelMember(args.ChannelId, args.Session.UserId)
 		if err != nil || channelMember == nil {
 			return &model.CommandResponse{
 				Text:         args.T("api.command_channel_header.permission.app_error"),
diff --git a/app/export.go b/app/export.go
index 18c11cbd52..4cb8c18ea9 100644
--- a/app/export.go
+++ b/app/export.go
@@ -5,7 +5,6 @@ package app
 
 import (
 	"encoding/json"
-	"errors"
 	"io"
 	"net/http"
 	"os"
@@ -13,6 +12,7 @@ import (
 	"strings"
 
 	"github.com/mattermost/mattermost-server/model"
+	"github.com/pkg/errors"
 )
 
 func (a *App) BulkExport(writer io.Writer, file string, pathToEmojiDir string, dirNameToExportEmoji string) *model.AppError {
@@ -404,8 +404,6 @@ func (a *App) createDirForEmoji(file string, dirName string) string {
 
 // Copies emoji files from 'data/emoji' dir to 'exported_emoji' dir
 func (a *App) copyEmojiImages(emojiId string, emojiImagePath string, pathToDir string) error {
-	var err error
-
 	fromPath, err := os.Open(emojiImagePath)
 	if fromPath == nil || err != nil {
 		return errors.New("Error reading " + emojiImagePath + "file")
@@ -414,12 +412,16 @@ func (a *App) copyEmojiImages(emojiId string, emojiImagePath string, pathToDir s
 
 	emojiDir := pathToDir + "/" + emojiId
 
-	if _, err := os.Stat(emojiDir); os.IsNotExist(err) {
-		os.Mkdir(emojiDir, os.ModePerm)
-	}
-	if err != nil {
-		return errors.New("Error creating directory for the emoji " + err.Error())
+	if _, err = os.Stat(emojiDir); err != nil {
+		if !os.IsNotExist(err) {
+			return errors.Wrapf(err, "Error fetching file info of emoji directory %v", emojiDir)
+		}
+
+		if err = os.Mkdir(emojiDir, os.ModePerm); err != nil {
+			return errors.Wrapf(err, "Error creating emoji directory %v", emojiDir)
+		}
 	}
+
 	toPath, err := os.OpenFile(emojiDir+"/image", os.O_RDWR|os.O_CREATE, 0666)
 	if err != nil {
 		return errors.New("Error creating the image file " + err.Error())
diff --git a/app/login.go b/app/login.go
index b7bd07fd13..01385e5429 100644
--- a/app/login.go
+++ b/app/login.go
@@ -45,8 +45,7 @@ func (a *App) AuthenticateUserForLogin(id, loginId, password, mfaToken string, l
 	}()
 
 	if len(password) == 0 {
-		err := model.NewAppError("AuthenticateUserForLogin", "api.user.login.blank_pwd.app_error", nil, "", http.StatusBadRequest)
-		return nil, err
+		return nil, model.NewAppError("AuthenticateUserForLogin", "api.user.login.blank_pwd.app_error", nil, "", http.StatusBadRequest)
 	}
 
 	// Get the MM user we are trying to login
diff --git a/app/notification_push.go b/app/notification_push.go
index af69452979..efe5970397 100644
--- a/app/notification_push.go
+++ b/app/notification_push.go
@@ -317,13 +317,14 @@ func ShouldSendPushNotification(user *model.User, channelNotifyProps model.Strin
 func DoesNotifyPropsAllowPushNotification(user *model.User, channelNotifyProps model.StringMap, post *model.Post, wasMentioned bool) bool {
 	userNotifyProps := user.NotifyProps
 	userNotify := userNotifyProps[model.PUSH_NOTIFY_PROP]
-	channelNotify, ok := channelNotifyProps[model.PUSH_NOTIFY_PROP]
+	channelNotify, _ := channelNotifyProps[model.PUSH_NOTIFY_PROP]
+	if channelNotify == "" {
+		channelNotify = model.CHANNEL_NOTIFY_DEFAULT
+	}
 
 	// If the channel is muted do not send push notifications
-	if channelMuted, ok := channelNotifyProps[model.MARK_UNREAD_NOTIFY_PROP]; ok {
-		if channelMuted == model.CHANNEL_MARK_UNREAD_MENTION {
-			return false
-		}
+	if channelNotifyProps[model.MARK_UNREAD_NOTIFY_PROP] == model.CHANNEL_MARK_UNREAD_MENTION {
+		return false
 	}
 
 	if post.IsSystemMessage() {
@@ -338,7 +339,7 @@ func DoesNotifyPropsAllowPushNotification(user *model.User, channelNotifyProps m
 		return false
 	}
 
-	if userNotify == model.USER_NOTIFY_MENTION && (!ok || channelNotify == model.CHANNEL_NOTIFY_DEFAULT) && !wasMentioned {
+	if userNotify == model.USER_NOTIFY_MENTION && channelNotify == model.CHANNEL_NOTIFY_DEFAULT && !wasMentioned {
 		return false
 	}
 
@@ -348,7 +349,7 @@ func DoesNotifyPropsAllowPushNotification(user *model.User, channelNotifyProps m
 	}
 
 	if userNotify == model.USER_NOTIFY_NONE &&
-		(!ok || channelNotify == model.CHANNEL_NOTIFY_DEFAULT) {
+		channelNotify == model.CHANNEL_NOTIFY_DEFAULT {
 		return false
 	}