`"Starting Manim..."` hangs -- if we start on class name

[VladimirFokow]

Steps to reproduce:

from manimlib import *

class MyScene(Scene):
    def construct(self):
        ## Test 1
        circle = Circle()
        self.play(ShowCreation(circle))

• put cursor on line 3 (line class MyScene(Scene):)
• run "Manim Notebook: Start scene at cursor"

The scene starts (as expected)
(with the command manimgl filename.py className) <-- note no -se lineNumber here,
     so the whole scene will be played,
     and then the terminal will be left in the interactive mode.

The Problem:
Notification "Starting Manim..." hangs.

(I didn't record the logs - I think it will be reproducible without them)

[Splines]

Yes, can reproduce, thanks for the report.