[REG 5.7.0 -> 5.7.1] Crash when using ShaderEffect on macOS

Steps to reproduce:

• open simple QML file (most of the stuff inside project tests/manual/qml/testfiles_quick2/testfiles_quick2.qmlproject should do) or create Quick application from template
• switch to Designer
• select a Rectangle, change its color with the property editor
• select another item inside the preview

Current result:

• QC crashes (not always, but if not, just repeat the above steps with other items on the same preview)