I get this error whenever i try and open a Kali terminal window. This is on an HTC Nexus 9 wifi. I can open an android terminal window just fine though.
When I look in /data/data/com.offsec.nethunter/ it is empty, so I believe it cant find bootkali, but im not anywhere smart enough to figure this out on my own sadly.
Reporting this as a possible bug as two other people in my office have nexus 9's and have the exact same issue.