##@, 4 bytes Although the language name is 1 byte, outputting the name is astonishingly difficult.

-{}0

This subtracts the string a by 0, which is undefined behavior and thus throws an error:

Traceback (most recent call last):
  File "@", line 477, in <module>
    res  = root.eval()
  File "@", line 413, in eval
    return self.ins.func(*self.argv, *self.insargs)
  File "@", line 115, in insHYPHEN
    raise TypeError('-')
TypeError: -

@, 4 bytes

Although the language name is 1 byte, outputting the name is astonishingly difficult.

-{}0

This subtracts the string a by 0, which is undefined behavior and thus throws an error:

Traceback (most recent call last):
  File "@", line 477, in <module>
    res  = root.eval()
  File "@", line 413, in eval
    return self.ins.func(*self.argv, *self.insargs)
  File "@", line 115, in insHYPHEN
    raise TypeError('-')
TypeError: -