[Sinner]

You're returning 2 types of data (1 is a string when you return "Result", the other one is a boolean when you return "false"). PAWN expects you to return the same data data type. A possible fix would be:

pawn Code:

stock Load(DataType[], Stat[], For[]) {
    new Result[128]; // Gets initialized to NULL
    if(strcmp(For, "None", true) == 0) {
        #pragma unused For
    }
    if(strcmp(DataType, "serverdata", true) == 0) {
        new Query[128];
        format(Query, 128, "SELECT * FROM serverdata LIMIT 1");
        mysql_query(Query);
        mysql_store_result();
        while(mysql_fetch_row_format(Query, "|")) {
            if(strcmp(Stat, "Name", true) == 0) {
                mysql_fetch_field_row(Result, "Name");
            }
            if(strcmp(Stat, "Mode", true) == 0) {
                mysql_fetch_field_row(Result, "Mode");
            }
            if(strcmp(Stat, "Map", true) == 0) {
                mysql_fetch_field_row(Result, "Map");
            }
        }
        mysql_free_result();
    }
    return Result; // Returns either the actual result or NULL
}

I hope that made sense, code is untested but should work fine.