For the code
  main() {
    while (1 < 2 < 3) {}
  }
the analyzer generates the following warnings:

[error] Expected to find ')' (/usr/local/google/home/lrn/dart/full/dart/dev/d2jspars.dart, line 2, col 15)
[error] Expected to find ';' (/usr/local/google/home/lrn/dart/full/dart/dev/d2jspars.dart, line 2, col 15)
[error] Expected a type name (/usr/local/google/home/lrn/dart/full/dart/dev/d2jspars.dart, line 2, col 17)
[error] Expected to find '>' (/usr/local/google/home/lrn/dart/full/dart/dev/d2jspars.dart, line 2, col 17)
[error] Expected a list or map literal (/usr/local/google/home/lrn/dart/full/dart/dev/d2jspars.dart, line 2, col 17)
[error] Expected to find ';' (/usr/local/google/home/lrn/dart/full/dart/dev/d2jspars.dart, line 2, col 17)
[error] Expected to find ';' (/usr/local/google/home/lrn/dart/full/dart/dev/d2jspars.dart, line 2, col 17)
[error] Expected an identifier (/usr/local/google/home/lrn/dart/full/dart/dev/d2jspars.dart, line 2, col 18)
[error] Unexpected token ')' (/usr/local/google/home/lrn/dart/full/dart/dev/d2jspars.dart, line 2, col 18)
[warning] The name '' is not a type and cannot be used as a parameterized type (/usr/local/google/home/lrn/dart/full/dart/dev/d2jspars.dart, line 2, col 17)
[warning] Undefined name '' (/usr/local/google/home/lrn/dart/full/dart/dev/d2jspars.dart, line 2, col 18)
9 errors and 2 warnings found.

It's very hard to figure out what the error is. If possible, make the error message more useful.