Improve error messages in pointer-to-bitvector casts in string operat…

…ions

Co-authored-by: Ryan Scott <[email protected]>

crucible-llvm/src/Lang/Crucible/LLVM/MemModel.hs

@@ -1136,7 +1136,7 @@ strLen bak mem = go (BV.zero PtrWidth) (truePred sym)
         do ast <- impliesPred sym cond loadok
            assert bak ast $ AssertFailureSimError "Error during memory load: strlen" ""
            v <- unpackMemValue sym (LLVMPointerRepr (knownNat @8)) llvmval
-           let err = AssertFailureSimError "Found pointer in string passed to `strlen`" ""
+           let err = AssertFailureSimError "Found pointer instead of byte in string passed to `strlen`" ""
            test <- bvIsNonzero sym =<< Partial.ptrToBv bak err v
            iteM bvIte sym
              test
@@ -1172,7 +1172,7 @@ loadString bak mem = go id
   go f _ (Just 0) = return $ f []
   go f p maxChars = do
      v <- doLoad bak mem p (bitvectorType 1) (LLVMPointerRepr (knownNat :: NatRepr 8)) noAlignment
-     let err = AssertFailureSimError "Found pointer when loading string" ""
+     let err = AssertFailureSimError "Found pointer instead of byte when loading string" ""
      x <- Partial.ptrToBv bak err v
      case BV.asUnsigned <$> asBV x of
        Just 0 -> return $ f []