Currently contract MultiHashWrapper is implemented as a contract. Because this module has no storage and no external functions, it is appropriate to implement this as a library.
Similarly for Spawner.

Recommendation: switch these to libraries
References:

• MultiHashWrapper implementation:

  erasure-protocol/contracts/modules/MultiHashWrapper.sol

  Line 10 in 4a3d98c

  contract MultiHashWrapper {

• Spawner implementation: https://github.com/erasureprotocol/erasure-protocol/blob/4a3d98ce023a264a9f3c7ba62ef77a9207bba5fe/contracts/modules/Spawner.sol