Error message - Error occurred when trying to execute widget

[daleksovski]

When several widgets are run one after another, and an error appears, the message "Error occurred when trying to execute widget ..." is shown (on the top of the screen, in red). However, it shows only the error of the last problematic widget (eg. The prerequisites for running this widget have not been met).
It will be more helpful to the user if the error of the first problematic widget is shown instead.