Handle errors correctly in `os_get_terminal_size_impl` in `posixmodule.c`

[sobolevn]

Bug report

Here the first possible error will be overwritten by the second one:

cpython/Modules/posixmodule.c

Lines 14981 to 14990 in 3cdfdc0

	termsize = PyStructSequence_New((PyTypeObject *)TerminalSizeType);
	if (termsize == NULL)
	return NULL;
	PyStructSequence_SET_ITEM(termsize, 0, PyLong_FromLong(columns));
	PyStructSequence_SET_ITEM(termsize, 1, PyLong_FromLong(lines));
	if (PyErr_Occurred()) {
	Py_DECREF(termsize);
	return NULL;
	}
	return termsize;

Linked PRs

• gh-116520: Fix error handling in os_get_terminal_size_impl in posixmodule #116521
• [3.12] gh-116520: Fix error handling in os_get_terminal_size_impl in posixmodule (GH-116521) #116539
• [3.11] gh-116520: Fix error handling in os_get_terminal_size_impl in posixmodule (GH-116521) #116540