IVGCVSW-7889 Add support for Signed64 data type in Cast layer

* Remove mention of "isDepthwise" variable name when not needed and therefore IgnoreUnused call
* Improve error messages and change them to throws in Encoder and Decoder

Signed-off-by: Teresa Charlin <teresa.charlinreyes@arm.com>
Change-Id: I8ce30b5075e1e47d54abc12390265ba8e9ee1405
diff --git a/src/backends/reference/workloads/DetectionPostProcess.cpp b/src/backends/reference/workloads/DetectionPostProcess.cpp
index 2108efe..c5ab327 100644
--- a/src/backends/reference/workloads/DetectionPostProcess.cpp
+++ b/src/backends/reference/workloads/DetectionPostProcess.cpp
@@ -6,6 +6,7 @@
 #include "DetectionPostProcess.hpp"
 
 #include <armnn/utility/Assert.hpp>
+#include <armnn/utility/IgnoreUnused.hpp>
 #include <armnn/utility/NumericCast.hpp>
 
 #include <algorithm>