Error fetching UnavailableBlockInput: Cannot read properties of undefined (reading 'data')

Found these in the logs
```
Jul-01 22:47:14.204[sync] debug: Error fetching UnavailableBlockInput attempt=0, blockRootHex=0xa716fedba9299af0f187feaeda3a999814fd1779785729385c3a8742845c6061, peer=16Uiu2HAm8NTb22bnv52PUrZ9dEzsEste2gsEdpCkiiFqaLpaLCqc - Cannot read properties of undefined (reading 'data')
TypeError: Cannot read properties of undefined (reading 'data')
at unavailableBeaconBlobsByRoot (file:///usr/app/packages/beacon-node/src/network/reqresp/beaconBlocksMaybeBlobsByRoot.ts:69:26)
at UnknownBlockSync.fetchUnavailableBlockInput (file:///usr/app/packages/beacon-node/src/sync/unknownBlock.ts:539:28)
at wrapError (file:///usr/app/packages/beacon-node/src/util/wrapError.ts:18:32)
at UnknownBlockSync.downloadBlock (file:///usr/app/packages/beacon-node/src/sync/unknownBlock.ts:295:13)
Jul-01 22:47:14.266[sync] debug: Error fetching UnavailableBlockInput attempt=1, blockRootHex=0xa716fedba9299af0f187feaeda3a999814fd1779785729385c3a8742845c6061, peer=16Uiu2HAm2YyKS58f5m4ZVqJswdwqoM8TodrfMynXjd7bzELSrgMm - Cannot read properties of undefined (reading 'data')
TypeError: Cannot read properties of undefined (reading 'data')
at unavailableBeaconBlobsByRoot (file:///usr/app/packages/beacon-node/src/network/reqresp/beaconBlocksMaybeBlobsByRoot.ts:69:26)
at UnknownBlockSync.fetchUnavailableBlockInput (file:///usr/app/packages/beacon-node/src/sync/unknownBlock.ts:539:28)
at wrapError (file:///usr/app/packages/beacon-node/src/util/wrapError.ts:18:32)
at UnknownBlockSync.downloadBlock (file:///usr/app/packages/beacon-node/src/sync/unknownBlock.ts:295:13)
```

Not sure if this is an actual issue but needs to be looked into.

cc @g11tech

Start in packages/beacon-node/src/network/reqresp/beaconBlocksMaybeBlobsByRoot.ts at unavailableBeaconBlobsByRoot, then follow its call from packages/beacon-node/src/sync/unknownBlock.ts:539 and the downloadBlock path at line 295. Determine why the response is undefined when fetching UnavailableBlockInput and establish the expected behavior for that case. Done means the fetch no longer produces this TypeError and the behavior is covered by an appropriate test.

Written by the indexing model from the issue text.