Fix memory leak

Author: rswave

Sources/CodeScanner/ScannerViewController.swift

@@ -457,7 +457,8 @@ extension CodeScannerView {
                 guard !isCapturing else { return }
                 isCapturing = true
 
-                handler = { [self] image in
+                handler = { [weak self] image in
+                    guard let self else { return }
                     let result = ScanResult(string: stringValue, type: readableObject.type, image: image, corners: readableObject.corners)
 
                     switch parentView.scanMode {