add errcheck validation

Signed-off-by: Emile Vauge <emile@vauge.com>

script/validate-errcheck

@@ -0,0 +1,28 @@
+#!/bin/bash
+
+source "$(dirname "$BASH_SOURCE")/.validate"
+
+IFS=$'\n'
+files=( $(validate_diff --diff-filter=ACMR --name-only -- '*.go' | grep -v '^vendor/' || true) )
+unset IFS
+
+errors=()
+failedErrcheck=$(errcheck .)
+if [ "$failedErrcheck" ]; then
+    errors+=( "$failedErrcheck" )
+fi
+
+if [ ${#errors[@]} -eq 0 ]; then
+	echo 'Congratulations!  All Go source files have been errchecked.'
+else
+	{
+		echo "Errors from errcheck:"
+		for err in "${errors[@]}"; do
+			echo "$err"
+		done
+		echo
+		echo 'Please fix the above errors. You can test via "errcheck" and commit the result.'
+		echo
+	} >&2
+	false
+fi