#This doesn't work

set -o errexit
trap 'catch $? $LINENO' EXIT
catch() {
  code="$1"
  echo "Exit code $code"
}
purposely break here

#The above will fail miserably on code="$1". The echo is never run, and the script exits on code=

#This works

set -o errexit
trap 'catch $? $LINENO' EXIT
catch() {
  local code="$1"
  echo "Exit code $code"
}
purposely break here
#Declaring code as a local variable works.
#If I put echo whatever before code= also works.
#I don't know why this fails, but I tried many variations of "why is this broken?", and my final answer is "bash trap function HATES global variable assignment as first line in the invoked trap function".