refactor(traceback): consolidate ModuleNotFoundError handling and fix suggestion formatting

Move ModuleNotFoundError stdlib module detection into the unified
suggestion handling block, removing duplicate exception handling code.

Also fix the site initialization disabled message to include virtual
environment hint and add proper handling for non-ASCII suggestion names
in the _suggestion_message function.

Author: krisztian-gajdar

Lib/traceback.py

@@ -1103,6 +1103,13 @@ def __init__(self, exc_type, exc_value, exc_traceback, *, limit=None,
                 self.msg = exc_value.msg
                 self._is_syntax_error = True
                 self._exc_metadata = getattr(exc_value, "_metadata", None)
+            elif (issubclass(exc_type, ModuleNotFoundError)
+                    and getattr(exc_value, "name", None) in sys.stdlib_module_names):
+                module_name = exc_value.name
+                self._str = _MISSING_STDLIB_MODULE_MESSAGES.get(
+                    module_name,
+                    f"Standard library module {module_name!r} was not found"
+                )
             elif suggestion := _suggestion_message(exc_type, exc_value, exc_traceback):
                 if self._str.endswith(('.', '?', '!')):
                     punctuation = ''
@@ -1113,56 +1120,6 @@ def __init__(self, exc_type, exc_value, exc_traceback, *, limit=None,
             self.exc_type_qualname = None
             self.exc_type_module = None
 
-        if exc_type and issubclass(exc_type, SyntaxError):
-            # Handle SyntaxError's specially
-            self.filename = exc_value.filename
-            lno = exc_value.lineno
-            self.lineno = str(lno) if lno is not None else None
-            end_lno = exc_value.end_lineno
-            self.end_lineno = str(end_lno) if end_lno is not None else None
-            self.text = exc_value.text
-            self.offset = exc_value.offset
-            self.end_offset = exc_value.end_offset
-            self.msg = exc_value.msg
-            self._is_syntax_error = True
-            self._exc_metadata = getattr(exc_value, "_metadata", None)
-        elif exc_type and issubclass(exc_type, ImportError) and \
-                getattr(exc_value, "name_from", None) is not None:
-            wrong_name = getattr(exc_value, "name_from", None)
-            suggestion = _compute_suggestion_error(exc_value, exc_traceback, wrong_name)
-            if suggestion:
-                if suggestion.isascii():
-                    self._str += f". Did you mean: '{suggestion}'?"
-                else:
-                    self._str += f". Did you mean: '{suggestion}' ({suggestion!a})?"
-        elif exc_type and issubclass(exc_type, ModuleNotFoundError):
-            module_name = getattr(exc_value, "name", None)
-            if module_name in sys.stdlib_module_names:
-                message = _MISSING_STDLIB_MODULE_MESSAGES.get(
-                    module_name,
-                    f"Standard library module {module_name!r} was not found"
-                )
-                self._str = message
-            elif sys.flags.no_site:
-                self._str += (". Site initialization is disabled, did you forget to "
-                    + "add the site-packages directory to sys.path "
-                    + "or to enable your virtual environment?")
-        elif exc_type and issubclass(exc_type, (NameError, AttributeError)) and \
-                getattr(exc_value, "name", None) is not None:
-            wrong_name = getattr(exc_value, "name", None)
-            suggestion = _compute_suggestion_error(exc_value, exc_traceback, wrong_name)
-            if suggestion:
-                if suggestion.isascii():
-                    self._str += f". Did you mean: '{suggestion}'?"
-                else:
-                    self._str += f". Did you mean: '{suggestion}' ({suggestion!a})?"
-            if issubclass(exc_type, NameError):
-                wrong_name = getattr(exc_value, "name", None)
-                if wrong_name is not None and wrong_name in sys.stdlib_module_names:
-                    if suggestion:
-                        self._str += f" Or did you forget to import '{wrong_name}'?"
-                    else:
-                        self._str += f". Did you forget to import '{wrong_name}'?"
         if lookup_lines:
             self._load_lines()
         self.__suppress_context__ = \
@@ -1798,7 +1755,8 @@ def _suggestion_message(exc_type, exc_value, exc_traceback):
         and getattr(exc_value, "name", None) not in sys.stdlib_module_names
     ):
         return ("Site initialization is disabled, did you forget to "
-            "add the site-packages directory to sys.path?")
+                    "add the site-packages directory to sys.path "
+                    "or to enable your virtual environment?")
     if issubclass(exc_type, (ImportError, NameError, AttributeError)):
         if issubclass(exc_type, ImportError):
             wrong_name = getattr(exc_value, "name_from", None)
@@ -1816,7 +1774,10 @@ def _suggestion_message(exc_type, exc_value, exc_traceback):
                 if maybe_stdlib_import:
                     return f"Did you forget to import '{wrong_name}'?"
                 return None
-            text = f"Did you mean: '{other_name}'?"
+            if other_name.isascii():
+                text = f"Did you mean: '{other_name}'?"
+            else:
+                text = f"Did you mean: '{other_name}' ({other_name!a})?"
             if maybe_stdlib_import:
                 return f"{text} Or did you forget to import '{wrong_name}'?"
             return text