This is an error that originates from Java code, typically concerning some GUI component that misbehavs or which does not handle some edge-case properly. You need to either adapt the way that you interact with that code (for example, ensure that you don't pass a Null pointer i.e. [] or {} as input argument), or ask the code's developers to handle this edge case.
Note that in a very large number of cases, you can safely ignore such command-window errors unless you see that there is really something wrong (for example, bad GUI rendering etc.). Yes they are indeed ugly and bothersome, but in many cases there are also harmless.
