tidy up location of args

build/root/install.sh

@@ -3,9 +3,22 @@
 # exit script if return code != 0
 set -e
 
-# release tag name from build arg, stripped of build ver using string manipulation
+# release tag name from buildx arg, stripped of build ver using string manipulation
 RELEASETAG="${1//-[0-9][0-9]/}"
 
+# target arch from buildx arg
+TARGETARCH="${2}"
+
+if [[ -z "${RELEASETAG}" ]]; then
+	echo "[warn] Release tag name from build arg is empty, exiting script..."
+	exit 1
+fi
+
+if [[ -z "${TARGETARCH}" ]]; then
+	echo "[warn] Target architecture name from build arg is empty, exiting script..."
+	exit 1
+fi
+
 # note do NOT download build scripts - inherited from int script with envvars common defined
 
 # get target arch from Dockerfile argument