Either pullup or pulldown resistors would have helped - you see this a lot in PCB design, even short traces that are used for signalling will be pulled low or h

Either pullup or pulldown resistors would have helped - you see this a lot in PCB design, even short traces that are used for signalling will be pulled low or high via a relatively high resistance. That ensures that you have a sharp transition when the switch or whatever is closed or opened and that a floating voltage can't appear over time on your line and cause false triggers.