This issue was originally filed by greg.g...@gmail.com

What steps will reproduce the problem?
1.
Start with the following program in the editor:
printNumber(num aNum){
  print("This is the number: $aNum");
}

void main() {
  const num number = 42;
  printNumber(number);
  
  printNumber(47);
}

2.
Run the program several times with the <command>R short cut. You'll need to let off the <command> key between runs.

What is the expected output? What do you see instead?

dart --enable-checked-mode HWCommandLine.dart

This is the number: 42
This is the number: 47
/Volumes/data/b/build/slave/dart-editor-mac/build/dart/runtime/platform/thread_macos.cc:201: error: pthread error: 16 (Resource busy)

What version of the product are you using? On what operating system?

Dart Editor version 0.1.2_r15912
Dart SDK version 0.1.2.0_r15912

[~]$ sw_vers
ProductName: Mac OS X
ProductVersion: 10.8.2
BuildVersion: 12C3012

Please provide any additional information below.