`tpx` command exits before a new instance is created

`tpx` is supposed to create a new powershell tab and then close the current one. However, it exits before it can create the tab if the current tab is the only tab in the only windows terminal window.

So, in other words, if there's only one windows terminal window open, with only one powershell tab, and you run `tpx` in that tab, then the command closes the current tab but never opens a new one.