SafeConnect double execution, stale connections, and SafeSlot override leakage

[wyzula-jan]

Description

Fix issues with SafeConnect, previously any SafeConnect slot would be executed twice and connections from the deleted widget would be still connected on Qt level.

[Copilot]

Pull request overview

This pull request fixes lifecycle and call-semantics issues in the SafeConnect/SafeSlot utilities to prevent double slot execution, avoid accumulating stale Qt connections, and ensure per-call overrides don’t mutate decorator defaults.

Changes:

• Reworked SafeConnect to invoke the target slot exactly once per signal emission (with payload), and to self-disconnect when the receiver/slot becomes stale.
• Updated SafeSlot to apply _override_slot_params on a per-call basis via a merged copy, preventing persistent mutation of decorator defaults.
• Added regression tests covering the above behaviors (single execution, stale connection cleanup, override leakage).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
tests/unit_tests/test_error_utils.py	Adds regression tests for SafeConnect single-execution + stale-disconnect behavior, and SafeSlot per-call override behavior.
bec_widgets/utils/error_popups.py	Fixes SafeConnect wrapper semantics and adds self-disconnect on stale refs; fixes SafeSlot override leakage by using per-call merged params.

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[codecov]

Codecov Report

❌ Patch coverage is 87.50000% with 2 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
bec_widgets/utils/error_popups.py	87.50%	2 Missing ⚠️

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[github-actions]

Benchmark comparison

Threshold: 20% (lower is better).
Result: 0 regression(s), 0 improvement(s) beyond threshold.

No benchmark regression exceeded the configured threshold.

No benchmark improvement exceeded the configured threshold.

All benchmark results

Benchmark	Baseline	Current	Change	Status
BEC IPython client with companion app	2.20399 s	2.01424 s	-8.61%	ok
BEC IPython client without companion app	2.18623 s	2.0226 s	-7.48%	ok
Import bec_widgets	0.0131978 s	0.0138056 s	+4.61%	ok
tests/unit_tests/benchmarks/test_dock_area_benchmark.py::test_add_waveform_to_dock_area	0.158608 s	0.145489 s	-8.27%	ok