Issuing adb shell commands with arguments
"-c" switch of sh command requires (and uses) a single argument which is the full shell command as a string.

This should do the trick:

adb shell run-as com.steenriver.littlecrane 'sh -c "ls files"'


In the original example, "files" is interpreted as an extra argument of the "sh" command (simply discarded when using the "-c" switch) , not of the "ls" command.