Expanding org chart node raises error

[mkoestner]

Describe the bug
Looks like a new bug in 15.4.0
If you try the component in the documentation you get the following error in the console:

in.df8ff6c401bed359.js:1 ERROR TypeError: r.className.indexOf is not a function
at n.onNodeClick (6909.995347ac501d0042.js:1:8737)
at n.onNodeClick (6909.995347ac501d0042.js:1:5249)
at 6909.995347ac501d0042.js:1:3440
at qm (main.df8ff6c401bed359.js:1:1398812)
at C (main.df8ff6c401bed359.js:1:1398979)
at HTMLDivElement. (main.df8ff6c401bed359.js:1:1487193)
at v.invokeTask (polyfills.592a92282d9cd7cd.js:1:7171)
at Object.onInvokeTask (main.df8ff6c401bed359.js:1:1428767)
at v.invokeTask (polyfills.592a92282d9cd7cd.js:1:7092)
at L.runTask (polyfills.592a92282d9cd7cd.js:1:2536)
handleError @ main.df8ff6c401bed359.js:1
Mm @ main.df8ff6c401bed359.js:1
qm @ main.df8ff6c401bed359.js:1
C @ main.df8ff6c401bed359.js:1
(anonymous) @ main.df8ff6c401bed359.js:1
invokeTask @ polyfills.592a92282d9cd7cd.js:1
onInvokeTask @ main.df8ff6c401bed359.js:1
invokeTask @ polyfills.592a92282d9cd7cd.js:1
runTask @ polyfills.592a92282d9cd7cd.js:1
invokeTask @ polyfills.592a92282d9cd7cd.js:1
O @ polyfills.592a92282d9cd7cd.js:1
N @ polyfills.592a92282d9cd7cd.js:1
B @ polyfills.592a92282d9cd7cd.js:1

Environment
Browser, PrimeNG

PrimeNG version
15.4.1

Steps to reproduce the behavior
Open the link above, open the browser console and then expand a node in the org chart