Exception stacktrace generated from passing an invalid `target` to `Thread(...).start()` does not include the line calling the `start()` method

import threading,sys
print(sys.version)
def ThreadMain():
    print("howdy cowboy")
ThreadMaiin=True

myThread=threading.Thread(target=ThreadMaiin)
myThread.start() # @note Ideally, the Stacktrace generated by the exception raised as a result of this line would include the line itself

Prints the following to console:

3.14.3 (tags/v3.14.3:323c59a, Feb  3 2026, 16:04:56) [MSC v.1944 64 bit (AMD64)]
Exception in thread Thread-1:
Traceback (most recent call last):
  File "C:\Users\olliv\AppData\Local\Programs\Python\Python314\Lib\threading.py", line 1082, in _bootstrap_inner
    self._context.run(self.run)
    ~~~~~~~~~~~~~~~~~^^^^^^^^^^
  File "C:\Users\olliv\AppData\Local\Programs\Python\Python314\Lib\threading.py", line 1024, in run
    self._target(*self._args, **self._kwargs)
    ~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
TypeError: 'bool' object is not callable

Linked PRs

• gh-145243

Start with threading.py, especially Thread.start(), _bootstrap_inner(), and run(), and inspect the linked work in gh-145243 before making changes. Reproduce the invalid-target example and trace how the worker exception is formatted; done means the traceback includes the caller's myThread.start() line without regressing normal thread exception reporting.