Fix Argument.__repr__ crash when _action is not initialized

changelog/13817.bugfix.rst

@@ -0,0 +1 @@
+Fixed a secondary `AttributeError` masking the original error when an option argument fails to initialize.

src/_pytest/config/argparsing.py

@@ -306,10 +306,13 @@ def type(self) -> Any | None:
         return self._action.type
 
     def __repr__(self) -> str:
+        action = getattr(self, "_action", None)
+        if action is None:
+            return "Argument(<uninitialized>)"
         args: list[str] = []
         args += ["opts: " + repr(self.names())]
         args += ["dest: " + repr(self.dest)]
-        if self._action.type:
+        if action.type:
             args += ["type: " + repr(self.type)]
         args += ["default: " + repr(self.default)]
         return "Argument({})".format(", ".join(args))

testing/test_parseopt.py

@@ -341,3 +341,28 @@ def test_argcomplete(pytester: Pytester, monkeypatch: MonkeyPatch) -> None:
     monkeypatch.setenv("COMP_POINT", str(len("pytest " + arg)))
     result = pytester.run("bash", str(script), arg)
     result.stdout.fnmatch_lines(["test_argcomplete", "test_argcomplete.d/"])
+
+
+def test_argument_repr_uninitialized() -> None:
+    """Argument.__repr__ should not crash if _action is not set yet."""
+    arg = parseopt.Argument.__new__(parseopt.Argument)
+    result = repr(arg)
+    assert result == "Argument(<uninitialized>)"
+
+
+def test_argument_repr_initialized(parser: parseopt.Parser) -> None:
+    """Argument.__repr__ works normally when properly initialized."""
+    parser.addoption("--myflag", dest="myflag", help="test flag")
+    option = parser._anonymous.options[-1]
+    result = repr(option)
+    assert "opts:" in result
+    assert "dest:" in result
+
+
+def test_argument_repr_with_type(parser: parseopt.Parser) -> None:
+    """Argument.__repr__ includes type when set."""
+    parser.addoption("--count", type=int, dest="count", help="count")
+    option = parser._anonymous.options[-1]
+    result = repr(option)
+    assert "type:" in result
+    assert "int" in result