Fix scrollview content staying non-interactive after slowly swiping down (#597)

This was noticed when updating contained SwiftUI views rapidly.

This change is what fixed a certain bug the scroll content can be locked at a negative offset. It was most obvious when the whitespace was large, hence the offset was something around -100.0. At the same time, the contents (like buttons) were non-interactive.

Co-authored-by: Sören Gade <soeren.gade@lichtblick.de>

Sources/Core.swift

@@ -1079,7 +1079,11 @@ class Core: NSObject, UIGestureRecognizerDelegate {
         // Must use setContentOffset(_:animated) to force-stop deceleration
         guard let scrollView = scrollView else { return }
         var offset = scrollView.contentOffset
-        setValue(contentOffset, to: &offset)
+        if contentOffset.y >= 0 {
+            setValue(contentOffset, to: &offset)
+        } else {
+            offset = CGPoint(x: 0, y: 0)
+        }
         scrollView.setContentOffset(offset, animated: false)
     }