When building up the InstructionList, BCEL has already done all those checks
mentioned in The Java Virtual Machine Specification, Second Edition, as
\"static constraints on the operands of instructions in the code array\".
TODO: see the do_verify() comments. Maybe we should really work on the
byte array first to give more comprehensive messages.
TODO: Review Exception API, possibly build in some \"offending instruction\" thing
when we're ready to insulate the offending instruction by doing the
above thing.