Adds better handling for files with invalid utf8 content

src/paperless_text/tests/samples/decode_error.txt

@@ -0,0 +1 @@
+Pantothens<EFBFBD>ure

src/paperless_text/tests/test_parser.py

@@ -1,4 +1,4 @@
-import os
+from pathlib import Path
 
 from django.test import TestCase
 
@@ -8,12 +8,14 @@ from paperless_text.parsers import TextDocumentParser
 
 
 class TestTextParser(DirectoriesMixin, FileSystemAssertsMixin, TestCase):
+    SAMPLE_DIR = Path(__file__).resolve().parent / "samples"
+
     def test_thumbnail(self):
         parser = TextDocumentParser(None)
 
         # just make sure that it does not crash
         f = parser.get_thumbnail(
-            os.path.join(os.path.dirname(__file__), "samples", "test.txt"),
+            self.SAMPLE_DIR / "test.txt",
             "text/plain",
         )
         self.assertIsFile(f)
@@ -22,9 +24,29 @@ class TestTextParser(DirectoriesMixin, FileSystemAssertsMixin, TestCase):
         parser = TextDocumentParser(None)
 
         parser.parse(
-            os.path.join(os.path.dirname(__file__), "samples", "test.txt"),
+            self.SAMPLE_DIR / "test.txt",
             "text/plain",
         )
 
         self.assertEqual(parser.get_text(), "This is a test file.\n")
         self.assertIsNone(parser.get_archive_path())
+
+    def test_parse_invalid_bytes(self):
+        """
+        GIVEN:
+            - Text file which contains invalid UTF bytes
+        WHEN:
+            - The file is parsed
+        THEN:
+            - Parsing continues
+            - Invalid bytes are removed
+        """
+        parser = TextDocumentParser(None)
+
+        parser.parse(
+            self.SAMPLE_DIR / "decode_error.txt",
+            "text/plain",
+        )
+
+        self.assertEqual(parser.get_text(), "Pantothensure\n")
+        self.assertIsNone(parser.get_archive_path())