    ﻿using System;
    using System.Collections.Generic;
    using System.Text;
    using System.Text.RegularExpressions;

    namespace Nikse.SubtitleEdit.Core.SubtitleFormats
    {
        public class UnknownSubtitle57 : SubtitleFormat
        {
            private static readonly Regex RegexTimeCodes = new Regex(@"^\d\d:\d\d:\d\d\.\d\d \d\d:\d\d:\d\d\.\d\d .+", RegexOptions.Compiled);

            public override string Extension => ".txt";

            public override string Name => "Unknown 57";

            public override string ToText(Subtitle subtitle, string title)
            {
                var sb = new StringBuilder();
                foreach (Paragraph p in subtitle.Paragraphs)
                {
                    //00:00:54.08 00:00:58.06 - Saucers... - ... a dry lake bed.  (newline is //)
                    sb.AppendLine($"{EncodeTimeCode(p.StartTime)} {EncodeTimeCode(p.EndTime)} {HtmlUtil.RemoveHtmlTags(p.Text).Replace(Environment.NewLine, "//")}");
                }
                return sb.ToString();
            }

            private static string EncodeTimeCode(TimeCode time)
            {
                //00:03:15.22 (last is frame)
                return $"{time.Hours:00}:{time.Minutes:00}:{time.Seconds:00}.{MillisecondsToFramesMaxFrameRate(time.Milliseconds):00}";
            }

            public override void LoadSubtitle(Subtitle subtitle, List<string> lines, string fileName)
            {
                //00:03:15.22 00:03:23.10 This is line one.//This is line two.
                _errorCount = 0;
                Paragraph p = null;
                subtitle.Paragraphs.Clear();
                char[] splitChars = { ':', '.' };
                foreach (string line in lines)
                {
                    var match = RegexTimeCodes.Match(line);
                    if (match.Success)
                    {
                        string temp = line.Substring(0, match.Length);
                        if (line.Length >= 23)
                        {
                            string text = line.Remove(0, 23).Trim();
                            if (!text.Contains(Environment.NewLine))
                                text = text.Replace("//", Environment.NewLine);
                            p = new Paragraph(DecodeTimeCodeFrames(temp.Substring(0, 11), splitChars), DecodeTimeCodeFrames(temp.Substring(12, 11), splitChars), text);
                            subtitle.Paragraphs.Add(p);
                        }
                    }
                    else if (string.IsNullOrWhiteSpace(line))
                    {
                    }
                    else if (p != null)
                    {
                        if (p.Text.Length < 200)
                            p.Text = (p.Text + Environment.NewLine + line).Trim();
                    }
                }

                subtitle.Renumber();
            }
        }
    }

↑ V3095 The 'line' object was used before it was verified against null. Check lines: 46, 55.