Strip NUL bytes from CSV input to prevent crash

When a CSV file contains NUL bytes the csv module raises
_csv.Error: line contains NUL, crashing the insert command without a
useful error message. Stripping \x00 from each line before passing it
to the reader preserves all meaningful data while matching the
behaviour users expect. Fixes #582.

sqlite_utils/cli.py

@@ -1237,7 +1237,10 @@ def insert_upsert_implementation(
                 csv_reader_args["delimiter"] = delimiter
             if quotechar:
                 csv_reader_args["quotechar"] = quotechar
-            reader = csv_std.reader(decoded, **csv_reader_args)  # type: ignore
+            reader = csv_std.reader(  # type: ignore
+                (line.replace("\x00", "") for line in decoded),
+                **csv_reader_args,
+            )
             first_row = next(reader)
             if no_headers:
                 headers = ["untitled_{}".format(i + 1) for i in range(len(first_row))]

tests/test_cli_insert.py

@@ -252,6 +252,23 @@ def test_insert_csv_empty_null(db_path, empty_null):
     ]
 
 
+def test_insert_csv_nul_bytes(db_path, tmpdir):
+    # Regression test for https://github.com/simonw/sqlite-utils/issues/582
+    # CSV files containing NUL bytes should be imported without crashing.
+    file_path = str(tmpdir / "nul.csv")
+    with open(file_path, "wb") as fp:
+        fp.write(b"id,name\n1,Al\x00ice\n2,Bob\n")
+    result = CliRunner().invoke(
+        cli.cli,
+        ["insert", db_path, "data", file_path, "--csv", "--no-detect-types"],
+        catch_exceptions=False,
+    )
+    assert result.exit_code == 0
+    db = Database(db_path)
+    rows = list(db["data"].rows)
+    assert rows == [{"id": "1", "name": "Alice"}, {"id": "2", "name": "Bob"}]
+
+
 @pytest.mark.parametrize(
     "input,args",
     (