Fixes critical warnings in move-to-monitor functionality
Replaces some g_return_val_if_fail
(and g_return_if_fail
) macros with if-conditions as they're just regular flow-control areas, whereas g_return_val_if_fail is meant for critical errors (and logs a critical msg on each such "failure").
Fixes the warnings in #694 (closed)
Edited by Nicholas Dahm