Improve install diagnostic when using curl

install.sh

@@ -2,13 +2,15 @@
 
 set -euo pipefail
 
+CURL="curl --show-error --silent --location"
+
 echo "downloading bash_unit"
 current_working_dir=$PWD
-tarball_urls=$(curl -s https://api.github.com/repos/pgrange/bash_unit/releases | grep tarball_url)
+tarball_urls=$($CURL https://api.github.com/repos/pgrange/bash_unit/releases | grep tarball_url)
 tarball_url=$(echo "$tarball_urls" | head -n 1 | cut -d '"' -f 4)
 tmp_dir=$(mktemp -d 2>/dev/null || mktemp -d -t 'tmpdir')
 cd "$tmp_dir" || exit
-curl -Ls "$tarball_url" | tar -xz -f -
+$CURL "$tarball_url" | tar -xz -f -
 find "${tmp_dir}" -maxdepth 2 -type f -name "bash_unit" -exec cp {} "${current_working_dir}" \;
 rm -rf "$tmp_dir"
 echo "thank you for downloading bash_unit, you can now run ./bash_unit"