message: avoid the unbound variable error
diff: #!/usr/bin/env bash
  -set -eux
  -
  TBF_HEADER=64
  +KERNEL_VERSION=""
  +
  +if [ ! -z $LIBTOCK_PLATFORM ]; then
  + # we are using libtock2
  + PLATFORM=$LIBTOCK_PLATFORM
  + TBF_HEADER=72
  + KERNEL_VERSION="--kernel-major 2 --kernel-minor 0"
  +fi
  +
  +set -eux
  artifact="$(basename $1)"
  rust_target_folder="$(cd $(dirname $1)/../.. && pwd -P)"
  @@ -16,13 +24,6 @@ if [ -z $KERNEL_HEAP_SIZE ]; then
  exit 1
  fi
  -if [ ! -z $LIBTOCK_PLATFORM ]; then
  - # we are using libtock2
  - PLATFORM=$LIBTOCK_PLATFORM
  - TBF_HEADER=72
  - KERNEL_VERSION="--kernel-major 2 --kernel-minor 0"
  -fi
  -
  case "${PLATFORM}" in
  "apollo3")
  tockloader_flags=""
  