Fix txt exception

Author: mantas-done

src/Code/Converters/TxtConverter.php

@@ -24,6 +24,9 @@ public function fileContentToInternalFormat($file_content, $original_file_conten
         $file_content2 = trim($file_content);
         $file_content2 = preg_replace("/\n+/", "\n", $file_content2);
         $lines = mb_split("\n", $file_content2);
+        if ($lines === false) {
+            throw new UserException("Can't get lines from this file");
+        }
 
         if (!self::doesFileUseTimestamps($lines)) {
             if (self::areEmptyLinesUsedAsSeparators($file_content)) {

tests/formats/TxtTest.php

@@ -3,6 +3,7 @@
 namespace Tests\Formats;
 
 use Done\Subtitles\Code\Converters\TxtConverter;
+use Done\Subtitles\Code\UserException;
 use Done\Subtitles\Subtitles;
 use PHPUnit\Framework\TestCase;
 use Helpers\AdditionalAssertionsTrait;
@@ -436,6 +437,17 @@ public function testParsesTimestampsWhenTheyAreIdentical()
         ], $actual);
     }
 
+    public function testWhenCantGetLinesReturnsUserException()
+    {
+        $this->expectException(UserException::class);
+
+        Subtitles::loadFromString('
+00:00:00.00,00:00:01.00
+rz´2_ÿ¿®ŽÖÅâÖÉ
+<b>a</b>
+        ')->getInternalFormat();
+    }
+
     // ---------------------------------- private ----------------------------------------------------------------------
 
     private static function generatedSubtitles()