Understanding the Processing of Variables Defined by If in a Function

Python is having trouble handling variables defined in if in the function.

We are creating the following programs:

目的:
Rename the png file in the same hierarchy folder or one lower hierarchy folder

• Use the radio button on TKinter to switch the designated hierarchy to [same hierarchy] [one lower hierarchy]
• Use widget variables to get folder paths
• /*.png and /*/*.png are stuck together and retrieved in glob

I'm a beginner, so I've tried many things that came to mind, but I'm having trouble getting nothing.

The code in question
This path has probably not been obtained and is empty.
What should I do?
The radio button value acquisition seems to be working properly, but when I checked the filelist, there was nothing in it.

def list_create():
    def get_file_path():
        path = ''
        folder_path = folder.get()
        if rename_type.get() == 1: 
            path = folder_path + '/*.png'
        elif rename_type.get() == 2: 
            path = folder_path + '/*/*.png'
        return path
    
    path = get_file_path()
    filelist = glob.glob(path)

We have extracted the parts that may be related to the following.Folder and rename_type are available here.

#widget variable
folder = tkinter.StringVar()
rename_type = tk.StringVar(value="Rename File")

#frame
frame = tk.Frame(window)
frame.pack(side=tk.TOP, pady=10)
part_rename_radiobutton = tk.Radiobutton(frame, text="個々", variable=rename_type, value=1)
export_rename_radiobutton = tk.Radiobutton(frame, text="まとめて", variable=rename_type, value=2)