Main: Handle errors propagated to main as "error" log messages

Implement general error handler which logs errors instead of simply printing it on the error console

added enhancement suggestion labels

assigned to @u.eisenbarth

changed milestone to %v0.4

created branch 209-main-handle-errors-propagated-to-main-as-error-log-messages to address this issue

mentioned in issue #210 (closed)

mentioned in merge request !140 (merged)

mentioned in commit be30c87b

closed with merge request !140 (merged)

mentioned in issue #212 (closed)