Fix output format bug when exception occurs during completion

This addresses GitHub Issue #1565: #1565

Author: tleonhardt

cmd2/cmd2.py

@@ -64,7 +64,7 @@
 )
 
 import rich.box
-from rich.console import Group, RenderableType
+from rich.console import Console, Group, RenderableType
 from rich.highlighter import ReprHighlighter
 from rich.rule import Rule
 from rich.style import Style, StyleType
@@ -1467,17 +1467,22 @@ def pwarning(
     def pexcept(
         self,
         exception: BaseException,
+        *,
+        console: Console | None = None,
         **kwargs: Any,  # noqa: ARG002
     ) -> None:
         """Print an exception to sys.stderr.
 
         If `debug` is true, a full traceback is also printed, if one exists.
 
         :param exception: the exception to be printed.
+        :param console: optional Rich console to use for printing. If None, a new Cmd2ExceptionConsole
+                        instance is created which writes to sys.stderr.
         :param kwargs: Arbitrary keyword arguments. This allows subclasses to extend the signature of this
                        method and still call `super()` without encountering unexpected keyword argument errors.
         """
-        console = Cmd2ExceptionConsole(sys.stderr)
+        if console is None:
+            console = Cmd2ExceptionConsole(sys.stderr)
 
         # Only print a traceback if we're in debug mode and one exists.
         if self.debug and sys.exc_info() != (None, None, None):
@@ -2555,9 +2560,9 @@ def complete(
                 # above the prompt so it remains in the scrollback.
                 if ex.apply_style:
                     # Render the error with style to a string using Rich
-                    console = ru.Cmd2GeneralConsole()
-                    with console.capture() as capture:
-                        console.print("\n" + err_str, style=Cmd2Style.ERROR)
+                    general_console = ru.Cmd2GeneralConsole()
+                    with general_console.capture() as capture:
+                        general_console.print("\n" + err_str, style=Cmd2Style.ERROR)
                     self.completion_header = capture.get()
 
                 # Otherwise, this is a hint that should be displayed below the prompt.
@@ -2566,8 +2571,11 @@ def complete(
             return None
         except Exception as ex:  # noqa: BLE001
             # Insert a newline so the exception doesn't print in the middle of the command line being tab completed
-            self.perror()
-            self.pexcept(ex)
+            exception_console = ru.Cmd2ExceptionConsole()
+            with exception_console.capture() as capture:
+                exception_console.print()
+                self.pexcept(ex, console=exception_console)
+            self.completion_header = capture.get()
             return None
 
     def in_script(self) -> bool:

tests/test_completion.py

@@ -262,10 +262,10 @@ def test_complete_exception(cmd2_app, capsys) -> None:
     begidx = endidx - len(text)
 
     first_match = complete_tester(text, line, begidx, endidx, cmd2_app)
-    _out, err = capsys.readouterr()
+    out, _err = capsys.readouterr()
 
     assert first_match is None
-    assert "IndexError" in err
+    assert "IndexError" in out
 
 
 def test_complete_macro(base_app, request) -> None: