Правильное поведение ловушек EXIT и ERR при использовании `set -eu`

#!/bin/bash
admin="foobar@gmail.com"
threshold="85"

df -l --output=source,pcent | while IFS=" %" read -r part i; do
    if [ $i -ge $threshold ] 2>/dev/null; then
        echo "$part is currently at ${i}%. An email has been sent to your             administrator." 
        mail -s "Critical Alert: $part is currently at ${i}%. Clear space immeadiately!" $admin
    fi
done