expanded message context to contain the roots, which will make it lon…

…g but useful.

Signed-off-by: Paul Harris <paul.harris@consensys.net>

ethereum/spec/src/main/java/tech/pegasys/teku/spec/datastructures/blocks/StateAndBlockSummary.java

@@ -39,8 +39,13 @@ protected StateAndBlockSummary(final BeaconBlockSummary blockSummary, final Beac
       // This check would allow a state to have an empty slot, and still be a valid block and state.
       checkArgument(
           latestBlockHeaderBodyRoot.equals(blockSummary.getBodyRoot()),
-          "Block root for the state must match the supplied state at slot "
-              + blockSummary.getSlot());
+          String.format(
+              "Latest Block body root %s in state at slot %s must match the block summary root. "
+                  + "Block slot %s, block body root %s",
+              latestBlockHeaderBodyRoot,
+              state.getSlot(),
+              blockSummary.getSlot(),
+              blockSummary.getBodyRoot()));
     }
     this.blockSummary = blockSummary;
     this.state = state;