Fix unit test failure.

Author: kevinbackhouse

unitTests/test_types.cpp

@@ -49,8 +49,8 @@ TEST(DataBuf, canBeConstructedFromExistingData) {
 TEST(DataBuf, tryingToAccessTooFarElementThrows) {
   const std::array<byte, 4> data{'h', 'o', 'l', 'a'};
   DataBuf instance(data.data(), data.size());
-  ASSERT_THROW([[maybe_unused]] auto d = instance.data(4), std::out_of_range);
-  ASSERT_THROW([[maybe_unused]] auto d = instance.c_data(4), std::out_of_range);
+  ASSERT_THROW([[maybe_unused]] auto d = instance.data(5), std::out_of_range);
+  ASSERT_THROW([[maybe_unused]] auto d = instance.c_data(5), std::out_of_range);
 }
 
 TEST(DataBuf, readUintFunctionsWorksOnExistingData) {