7702: don't allow designator loops

EIPS/eip-7702.md

@@ -71,6 +71,8 @@ The delegation designation uses the banned opcode `0xef` from [EIP-3541](./eip-3
 
 For example, `EXTCODESIZE` would return the size of the code pointed to by `address` instead of `24` which would represent the delegation designation. `CALL` would similarly load the code from `address` and execute it in the context of `authority`.
 
+In case a delegation designator points to another designator, creating a potential chain or loop of designators, clients must retrieve only the first code and then stop following the designator chain.
+
 #### Gas Costs
 
 The intrinsic cost of the new transaction is inherited from [EIP-2930](./eip-2930.md), specifically `21000 + 16 * non-zero calldata bytes + 4 * zero calldata bytes + 1900 * access list storage key count + 2400 * access list address count`. Additionally, we add a cost of `PER_CONTRACT_CODE_BASE_COST * authorization list length`.