Fix the telnet console shutdown error after a failed start (#7910)

scrapy/extensions/telnet.py

@@ -52,6 +52,7 @@ class TelnetConsole(protocol.ServerFactory):
 
         self.crawler: Crawler = crawler
         self.noisy: bool = False
+        self.port: Port | None = None
         self.portrange: list[int] = [
             int(x) for x in crawler.settings.getlist("TELNETCONSOLE_PORT")
         ]
@@ -71,7 +72,7 @@ class TelnetConsole(protocol.ServerFactory):
         return cls(crawler)
 
     def start_listening(self) -> None:
-        self.port: Port = listen_tcp(self.portrange, self.host, self)
+        self.port = listen_tcp(self.portrange, self.host, self)
         h = self.port.getHost()
         logger.info(
             "Telnet console listening on %(host)s:%(port)d",
@@ -80,7 +81,10 @@ class TelnetConsole(protocol.ServerFactory):
         )
 
     def stop_listening(self) -> None:
-        self.port.stopListening()
+        # The port is unset if start_listening() failed, e.g. because every
+        # port in TELNETCONSOLE_PORT was taken.
+        if self.port is not None:
+            self.port.stopListening()
 
     def protocol(self) -> telnet.TelnetTransport:
         class Portal:

tests/test_extension_telnet.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+import socket
 from contextlib import contextmanager
 from typing import TYPE_CHECKING, Any
 
@@ -91,6 +92,18 @@ def test_invalid_reversed_portrange() -> None:
         console.start_listening()
 
 
+@coroutine_test
+async def test_unavailable_port(caplog: pytest.LogCaptureFixture) -> None:
+    """Run a crawl where the console cannot bind any port."""
+    with socket.create_server(("127.0.0.1", 0)) as sock:
+        port = sock.getsockname()[1]
+        crawler = _get_crawler(settings_dict={"TELNETCONSOLE_PORT": [port]})
+        await crawler.crawl_async()
+
+    assert "CannotListenError" in caplog.text
+    assert "AttributeError" not in caplog.text
+
+
 @coroutine_test
 async def test_telnet_vars() -> None:
     """Log into the console of a running crawl, which is when the telnet