java.lang.NullPointerException

[lubaarbel]

In my app Google console crashes reports there is the following log on wide variety of devices and OS versions:
java.lang.NullPointerException:
at com.stericson.RootShell.execution.Shell$1.run (Shell.java:594)
at java.lang.Thread.run (Thread.java:919)

I use version 1.6.
More stack trace:

java.lang.Object | Object.java in java.lang.Object.wait()
java.lang.Object | Object.java line 407 in java.lang.Object.wait()
com.ster...ootShell | RootShell.java line 582 in com.stericson.RootShell.RootShell.commandWait()
com.ster...ootShell | RootShell.java line 246 in com.stericson.RootShell.RootShell.findBinary()
com.ster...ootShell | RootShell.java line 196 in com.stericson.RootShell.RootShell.findBinary()
com.ster...ootShell | RootShell.java line 453 in com.stericson.RootShell.RootShell.isRootAvailable()