In some circumstances the chargers internal fuse may fail. If the fuse fails it could potentially result in damage to connected devices, or cause an electric shock.
What to do...
Stop using your wall charger. Dispose of the wall charger, but first - take a photo of it with your phone or another camera and fill in the online form to organise for a replacement. Alternatively, you can return it to the store where purchased to organise a replacement.