fix warnings

Fix a couple warnings so we can use meson warning level 3.  Instances of
the following warnings are found and resolved:

  Wreorder
  Wsign-compare

Change-Id: Ia223b42aa6bf743cfa0e7042cc3d5a18977459be
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/include/ADCSensor.hpp b/include/ADCSensor.hpp
index 39b9aaa..dfd8713 100644
--- a/include/ADCSensor.hpp
+++ b/include/ADCSensor.hpp
@@ -69,7 +69,7 @@
     boost::asio::deadline_timer waitTimer;
     boost::asio::streambuf readBuf;
     std::string path;
-    int errCount;
+    size_t errCount;
     double scaleFactor;
     std::optional<BridgeGpio> bridgeGpio;
     PowerState readState;