Error from the FindReplace widget when closing a project

What steps will reproduce the problem?

• Open a project
• Use the FindReplace widget in some file
• Close the project

However, I have closed a project before with the find widget still being visible so this issue could be difficult to reproduce?

Having validations for the editor existence all around the find widget logic could make sense

Traceback (most recent call last):
  File "C:\Users\dalth\AppData\Local\spyder-6\envs\spyder-runtime\Lib\site-packages\spyder\widgets\findreplace.py", line 774, in update_matches
    number_matches = self.editor.get_number_matches(
                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: 'NoneType' object has no attribute 'get_number_matches'

Setup info

• Spyder version: 6.1.0 (standalone)
• Python version: 3.12.11 64-bit
• Qt version: 5.15.15
• PyQt5 version: 5.15.11
• Operating System: Windows-10-10.0.19045-SP0