"Uncaught Sortable: el must be HTMLElement, and not [object Null]" JavaScript error on empty Deployment Plan page

[Piedone]

Describe the bug

When visiting a Deployment Plan's admin page that doesn't have any steps, you'll get the "Uncaught Sortable: el must be HTMLElement, and not [object Null]" JavaScript error.

To Reproduce

1. Create a Deployment Plan.
2. Manage Steps. Note how there are no steps yet.
3. See the below error in the browser console.

jquery.js?v=iYM10RZE7Ntlfp2wdKABGffCnB_klIVCaQBgUZr0r38:3138 Uncaught Sortable: `el` must be HTMLElement, and not [object Null]
(anonymous) @ jquery.js?v=iYM10RZE7Ntlfp2wdKABGffCnB_klIVCaQBgUZr0r38:3138
setTimeout (async)
jQuery.readyException @ jquery.js?v=iYM10RZE7Ntlfp2wdKABGffCnB_klIVCaQBgUZr0r38:3137
(anonymous) @ jquery.js?v=iYM10RZE7Ntlfp2wdKABGffCnB_klIVCaQBgUZr0r38:3151
mightThrow @ jquery.js?v=iYM10RZE7Ntlfp2wdKABGffCnB_klIVCaQBgUZr0r38:2911
process @ jquery.js?v=iYM10RZE7Ntlfp2wdKABGffCnB_klIVCaQBgUZr0r38:2959
setTimeout (async)
(anonymous) @ jquery.js?v=iYM10RZE7Ntlfp2wdKABGffCnB_klIVCaQBgUZr0r38:2999
fire @ jquery.js?v=iYM10RZE7Ntlfp2wdKABGffCnB_klIVCaQBgUZr0r38:2691
fireWith @ jquery.js?v=iYM10RZE7Ntlfp2wdKABGffCnB_klIVCaQBgUZr0r38:2803
fire @ jquery.js?v=iYM10RZE7Ntlfp2wdKABGffCnB_klIVCaQBgUZr0r38:2810
fire @ jquery.js?v=iYM10RZE7Ntlfp2wdKABGffCnB_klIVCaQBgUZr0r38:2691
fireWith @ jquery.js?v=iYM10RZE7Ntlfp2wdKABGffCnB_klIVCaQBgUZr0r38:2803
process @ jquery.js?v=iYM10RZE7Ntlfp2wdKABGffCnB_klIVCaQBgUZr0r38:2975
setTimeout (async)
(anonymous) @ jquery.js?v=iYM10RZE7Ntlfp2wdKABGffCnB_klIVCaQBgUZr0r38:2999
fire @ jquery.js?v=iYM10RZE7Ntlfp2wdKABGffCnB_klIVCaQBgUZr0r38:2691
fireWith @ jquery.js?v=iYM10RZE7Ntlfp2wdKABGffCnB_klIVCaQBgUZr0r38:2803
fire @ jquery.js?v=iYM10RZE7Ntlfp2wdKABGffCnB_klIVCaQBgUZr0r38:2810
fire @ jquery.js?v=iYM10RZE7Ntlfp2wdKABGffCnB_klIVCaQBgUZr0r38:2691
fireWith @ jquery.js?v=iYM10RZE7Ntlfp2wdKABGffCnB_klIVCaQBgUZr0r38:2803
ready @ jquery.js?v=iYM10RZE7Ntlfp2wdKABGffCnB_klIVCaQBgUZr0r38:3177
completed @ jquery.js?v=iYM10RZE7Ntlfp2wdKABGffCnB_klIVCaQBgUZr0r38:3186

Expected behavior

No errors in the console.

Screenshots