raise required PHP version from 7.0 to 7.2
We have nullable and void return types, so we can annotate almost every method (some union and mixed types missing, those are PHP 8 features)
add type hints where possible
remote redundant type checks in method bodies
use null coalescing operator (??) where applicable
Fixed 2 minor bugs that came up during this refactoring:
add missing return statement to Linkback::process()
ensure $implements_interface is initialized in ComponentHelper
based on #575, #576 and #579 (all merged)
??) where applicableFixed 2 minor bugs that came up during this refactoring:
Linkback::process()$implements_interfaceis initialized inComponentHelper