private static TypeBearer throwSimException(int idx, String msg) {
    throw new SimException("local " + Hex.u2(idx) + ": " + msg);
  }
Throws a properly-formatted exception.

@param idx the salient local index
@param msg {@code non-null;} useful message
@return never (keeps compiler happy)
android/android_framework/dex-maker/src/main/java/com/android/dx/cf/code/OneLocalsArray.java