Plots not updated when the source spreadsheet is deleted

Requirements

• I searched through the issues if the issue already exists

Steps to reproduce

1. Create a spreadsheet with some data
2. Plot this data, for example with a xy-curve
3. delete the spreadsheet

Expected

The plot/curve has to be properly updated and not data is ploted.

Observed

The curve is not updated, the old data is still shown. This is a regression from 2.10.

LabPlot Version

Debug build 2.10.0-2302-gb391222bd
Apr 15 2024, 21:19:18
System: openSUSE Leap 15.5
Locale: English,United States (Decimal point '.', Group separator ','
Number settings: Decimal point '.', Group separator ',', Exponential 'e', Zero digit '0', Percent '%', Positive/Negative sign '+'/'-' (Updated on restart)
Architecture: x86_64-little_endian-lp64
Kernel: linux 5.14.21-150500.55.52-default
C++ Compiler: GNU 12.3.0
C++ Compiler Flags: -fno-operator-names -fno-exceptions -Wall -Wextra -Wcast-align -Wchar-subscripts -Wformat-security -Wno-long-long -Wpointer-arith -Wundef -Wnon-virtual-dtor -Woverloaded-virtual -Werror=return-type -Werror=init-self -Wvla -Wdate-time -Wsuggest-override -Wlogical-op -Wall -Wextra -Wundef -Wpointer-arith -Wunreachable-code -Wunused -Wdeprecated-declarations -fno-omit-frame-pointer -fstack-protector -fexceptions -std=c++17 -O2 -Wcast-align -Wswitch-enum -fvisibility=default -pedantic -Wzero-as-null-pointer-constant