Handling errors in bash scripts

red=`echo -en "\e[31m"`
normal=`echo -en "\e[0m"`

# fatal uses SIGUSR1 to allow clean fatal errors
trap "exit 1" 10
PROC=$$ # this will get the current bash script id

function error(){
  echo -e "${red}$@${normal}" >&2
#  exit 1
  kill -10 $PROC
}

[[ "$1" ]] || error "Error:\nInput file needed\nExample: $0 'file.txt'"
[[ -f "$1" ]] || error "'${1}' file does not exist."

[[ "$2" ]] || (echo "Thank you for your input";error "'$1' exists";echo "Exiting Script")

echo "This should never output"