how to selectively add a key, if it exists?

[mahvar]

I need to merge two YAMLs in a very specific way this is the simplified version of what I'm doing

yq eval '
  load(strenv(first_file)) as $in1 |
  load(strenv(second_file)) as $in2 |
  {
    "components": {
      "schemas": {
        ($in1.title): {
          "key": "value"
        },
        ($in2.title): {
          "key": "value"
        }
      } +  $in1.components + $in2.components
    }
  }
' /dev/null 

It works perfectly as long as both files have components. How can I selectively add $in1.components and $in2.components only if they exist?

[mahvar]

Looks like using + ($in1.components // {}) + ($in2.components // {}) does the trick