Never garage your EV in an attached garage, nor an E-Bike. Keep EVs at least 50ft from your home. No, I don’t/won’t own one of those POS things.
The OEM e-bike charger and battery, unless damaged, are practically risk-free if used in specified ambient conditions (i.e. not extremely hot or cold or wet) and disconnected when charge is completed for extra margin of safety. The danger is certainly lower than other common situations (e.g. 5 gallons of gas in container in garage).