Don't return error if already part of channel being joined (#2814)

store/sql_channel_store.go

@@ -12,6 +12,7 @@ import (
 
 const (
 	MISSING_CHANNEL_ERROR = "store.sql_channel.get_by_name.missing.app_error"
+	MISSING_MEMBER_ERROR  = "store.sql_channel.get_member.missing.app_error"
 )
 
 type SqlChannelStore struct {
@@ -572,9 +573,13 @@ func (s SqlChannelStore) GetMember(channelId string, userId string) StoreChannel
 		result := StoreResult{}
 
 		var member model.ChannelMember
-		err := s.GetReplica().SelectOne(&member, "SELECT * FROM ChannelMembers WHERE ChannelId = :ChannelId AND UserId = :UserId", map[string]interface{}{"ChannelId": channelId, "UserId": userId})
-		if err != nil {
-			result.Err = model.NewLocAppError("SqlChannelStore.GetMember", "store.sql_channel.get_member.app_error", nil, "channel_id="+channelId+"user_id="+userId+","+err.Error())
+
+		if err := s.GetReplica().SelectOne(&member, "SELECT * FROM ChannelMembers WHERE ChannelId = :ChannelId AND UserId = :UserId", map[string]interface{}{"ChannelId": channelId, "UserId": userId}); err != nil {
+			if err == sql.ErrNoRows {
+				result.Err = model.NewLocAppError("SqlChannelStore.GetMember", MISSING_MEMBER_ERROR, nil, "channel_id="+channelId+"user_id="+userId+","+err.Error())
+			} else {
+				result.Err = model.NewLocAppError("SqlChannelStore.GetMember", "store.sql_channel.get_member.app_error", nil, "channel_id="+channelId+"user_id="+userId+","+err.Error())
+			}
 		} else {
 			result.Data = member
 		}