jq-front fails to process with ERROR: Failed to merge object nodes: about jq-front

[dakusui]

This appears to be an issue which is observed for merging incompatible nodes.
That is, given, a.json and b.json, each of which is a JSON object.
And at the same path .node, b.json has an array and the other has an atom (string, number, ...).

[dakusui]

#!/bin/env bash                                                                                                                                                                                             
set -eu +o posix -o pipefail

function debug() {
  echo "${@}" >&2
}

function abort() {
  debug "${@}"
  exit 1
}

# Latter overrides former                                                                                                                                                                                   
function _merge_object_nodes() {

  local _a="${1}"
  local _b="${2}"
  local _error
  _error=$(mktemp)
  debug "merging _a:'${_a}' and _b:'${_b}'"
  # shellcheck disable=SC2016                                                                                                                                                                               
  jq -r -c -n --argjson a "${_a}" --argjson b "${_b}" '#----                                                                                                                                                
def value_at($n; $p):                                                                                                                                                                                       
  $n | getpath($p);                                                                                                                                                                                         
                                                                                                                                                                                                            
def setvalue_at($n; $p; $v):                                                                                                                                                                                
  $n | setpath($p; $v);                                                                                                                                                                                     
                                                                                                                                                                                                            
def type_of($v):                                                                                                                                                                                            
  $v | type;                                                                                                                                                                                                
                                                                                                                                                                                                            
def setvalue_at($n; $p; $v):                                                                                                                                                                                
  $n | if type_of($v)=="object" or type_of($v)=="array" then                                                                                                                                                
         if type_of(value_at($n; $p))!="object" and type_of(value_at($n; $p)!="array") then                                                                                                                 
           setvalue_at(.; $p; $v)                                                                                                                                                                           
         else                                                                                                                                                                                               
           .                                                                                                                                                                                                
         end                                                                                                                                                                                                
       else                                                                                                                                                                                                 
         setvalue_at(.; $p; $v)                                                                                                                                                                             
       end;                                                                                                                                                                                                 
                                                                                                                                                                                                            
def merge_objects($a; $b):                                                                                                                                                                                  
  $b | [paths(scalars_or_empty)]                                                                                                                                                                            
     | reduce .[] as $p ($a; setvalue_at(.; $p; value_at($b; $p)));                                                                                                                                         
                                                                                                                                                                                                            
merge_objects($a; $b)' || {
    abort "Failed to merge object nodes:'${_a}' and '${_b}': error: ${_error}"
  }
}

_merge_object_nodes '{"key":"value"}' '{"key":["elem1"]}'