fix reaction's name validation with + sign in it (#6221)

model/reaction.go

@@ -6,6 +6,7 @@ package model
 import (
 	"encoding/json"
 	"io"
+	"regexp"
 )
 
 type Reaction struct {
@@ -60,7 +61,9 @@ func (o *Reaction) IsValid() *AppError {
 		return NewLocAppError("Reaction.IsValid", "model.reaction.is_valid.post_id.app_error", nil, "post_id="+o.PostId)
 	}
 
-	if len(o.EmojiName) == 0 || len(o.EmojiName) > 64 || !IsValidAlphaNumHyphenUnderscore(o.EmojiName, false) {
+	validName := regexp.MustCompile(`^[a-zA-Z0-9\-\+_]+$`)
+
+	if len(o.EmojiName) == 0 || len(o.EmojiName) > 64 || !validName.MatchString(o.EmojiName) {
 		return NewLocAppError("Reaction.IsValid", "model.reaction.is_valid.emoji_name.app_error", nil, "emoji_name="+o.EmojiName)
 	}