No, it is not safe to leave a toaster on overnight, especially with a piece of burnt toast inside. Leaving any electrical appliance unattended and powered on for an extended period poses a significant fire hazard.
Toasters are designed to toast bread slices quickly and efficiently. When you leave a toaster on for an extended period, it increases the risk of overheating and potentially catching fire. The presence of burnt toast further exacerbates the risk as burnt items are more likely to ignite.
Leaving any appliance, including toasters, unattended overnight can lead to potentially disastrous consequences, such as fire, smoke damage, or even endangering lives if the fire spreads.
It is essential to practice good safety habits with electrical appliances. Always unplug your toaster when not in use, clean it regularly to remove crumbs or debris, and never leave it running without supervision, especially overnight. If you do want to reheat or toast something in the morning, be sure to do so while you're awake and attentive to the process.