The subshell's trap is caught by the main shell, but the -E option is not used

function set_trap_for_exception() {
  function _on_error() {
    echo "error start"
    exit 1
  }
  trap '_on_error "$BASH_COMMAND" $LINENO' ERR
}



function is_hygon_cpu() {
  vendor_id=$(lscpu | grep "value is not exist")
}

function main()
{
        set_trap_for_exception
        is_hygon_cpu

}

main

cmd: vendor_id=$(lscpu | grep "value is not exist") will error but -E is not set, output is: error start

if i put echo in function is_hygon_cpu, subshell is not trap:

function set_trap_for_exception() {
  function _on_error() {
    echo "error start"
    exit 1
  }
  trap '_on_error "$BASH_COMMAND" $LINENO' ERR
}



function is_hygon_cpu() {
 echo "start"
 vendor_id=$(lscpu | grep "value is not exist")
 echo "end"
}

function main()
{
        set_trap_for_exception
        is_hygon_cpu

}

main

output is: start end

By default, the subshell will not inherit the main shell's traps, but this phenomenon really makes me confused. Why does this happen? Do commands in and out of functions have any effect on traps? Why can't I capture them if I add an echo?

Bash Manual Shell Functions

If a numeric argument is given to return, that is the function’s return status; otherwise the function’s return status is the exit status of the last command executed before the return.

so

function is_hygon_cpu() {
  vendor_id=$(lscpu | grep "value is not exist")
}

# return 1

function is_hygon_cpu() {
 echo "start"
 vendor_id=$(lscpu | grep "value is not exist")
 echo "end"
}

# return 0