how did you even succeed in doing that!
it is literary impossible to do so because a litecoin address is starting with the letter L
for example: LWdfXUxLBV9nCJ6yk5Ed2pBNhiV7kTaTQJ
and there is a checksum in the address that any wallet uses to verify if the address is valid before letting the user to send anything.
at the same time ethereum addresses are called accounts and start with the hex mark 0x
for example: 0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe and don't have checksum so if you put that in the withdrawal address of a litecoin wallet it will reject it.
so unless i am missing something since i am not completely familiar with ETH that is coinbase's fault for not validating the address before allowing you to withdraw.