Play it safe with null tokens/nodes (#24910).

Play it safe with null tokens/nodes (#24910).

Background here: https://github.com/dart-lang/sdk/issues/24910

The rub is we need to be careful in case nodes or tokens are null (for example when analyzing invalid source).

BUG=24910
R=scheglov@google.com

Committed: https://github.com/dart-lang/linter/commit/4640d54ce6df882392a75b7e90ee6a04e278f393

[pquitslund, 2015-11-22 03:30:52]

pquitslund@google.com changed reviewers:
+ scheglov@google.com

[scheglov, 2015-11-22 03:32:49]

LGTM

At some point it would be nice to write a test that exposes the NPE you're
fixing now.
But not today :-)

[pquitslund, 2015-11-22 03:42:26]

On 2015/11/22 03:32:49, scheglov wrote:
> LGTM

Thanks!

> At some point it would be nice to write a test that exposes the NPE you're
> fixing now.
> But not today :-)

Agreed!  I was thinking about this.  Some tests with invalid source would be
great.  Do you do any similar guarding in analyzer?  Any tests over invalid
source?

[pquitslund, 2015-11-22 03:43:41]

Committed patchset #1 (id:1) manually as
4640d54ce6df882392a75b7e90ee6a04e278f393 (presubmit successful).

[scheglov, 2015-11-22 03:46:22]

On 2015/11/22 03:42:26, pquitslund wrote:
> On 2015/11/22 03:32:49, scheglov wrote:
> > LGTM
> 
> Thanks!
> 
> > At some point it would be nice to write a test that exposes the NPE you're
> > fixing now.
> > But not today :-)
> 
> Agreed!  I was thinking about this.  Some tests with invalid source would be
> great.  Do you do any similar guarding in analyzer?  Any tests over invalid
> source?

Sometimes.
See usages of the AbstractSingleUnitTest.verifyNoTestUnitErrors field.