In some cases, several barcode widgets can be found on the same page.
This is for example the case of the stock picking: there is a widget on
the `stock.picking` model (main view) itself, and a widget on the
`stock.pack.operation` model (modal view).
In this case, when the focus is not set directly on the field which
needs to be filled in, both widgets will trigger a `barcode_scanned`
scanned event. This will call the `on_barcode_scanned` Python method
which can lead to errors/warning. For example, the `on_barcode_scanned`
method on the `stock.picking` model raises a warning in case the barcode
scanned does not match any product/package.
The fix is to make sure that the event target is located in the correct
DOM element.
opw-677506