eeschema: crash on second simulation

Description

Crash on simulation after schematics change

Steps to reproduce

1. create schematics, simulate.
2. Do not close simulation window, go to schematics, change any symbol value
3. go to simulation window, press "Run/Stop simulation icon"

KiCad Version

Application: KiCad Schematic Editor

Version: (6.99.0-2731-gf5283c6133), debug build

Libraries:
	wxWidgets 3.0.4
	FreeType 2.10.1
	HarfBuzz 2.6.4
	FontConfig 2.13.1

Platform: Linux 5.13.0-44-generic x86_64, 64 bit, Little endian, wxGTK, cinnamon, x11

	wxWidgets: 3.0.4 (wchar_t,wx containers,compatible with 2.8) GTK+ 3.24
	Boost: 1.71.0
	OCC: 7.5.2
	Curl: 7.68.0
	ngspice: 31
	Compiler: GCC 9.4.0 with C++ ABI 1013

Build settings:
	KICAD_USE_OCC=ON
	KICAD_SPICE=ON
	KICAD_STDLIB_DEBUG=OFF
	KICAD_STDLIB_LIGHT_DEBUG=OFF
	KICAD_SANITIZE_ADDRESS=OFF
	KICAD_SANITIZE_THREADS=OFF