I was compiling the cubescript example directly via the command line and encountered this:
Assertion failed: Failed to find the # of uses of var: $0
Stack: Error
at assertTrue (utility.js:60:23)
at analyzer.js:271:13
at Array.forEach (native)
at analyzer.js:260:20
at Array.forEach (native)
at Object.processItem (analyzer.js:238:22)
at Object.process (framework.js:155:26)
at framework.js:104:25
at Array.forEach (native)
at Object.solve (framework.js:92:27)
utility.js:61: Assertion failed: Failed to find the # of uses of var: $0
throw msg;
^