Update processFont to handle null expressions. (#186)

* Update processFont to handle null expressions.

* Guidelines.

CHANGELOG.md

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 071dad0..39c84cb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,7 @@
 ## 1.0.1-wip
 
-- Require Dart 3.0
+- Update `ExpressionsProcessor.processFont` to handle null expressions.
+- Require Dart 3.0.
 
 ## 1.0.0
 

lib/parser.dart

diff --git a/lib/parser.dart b/lib/parser.dart
index e978069..837007d 100644
--- a/lib/parser.dart
+++ b/lib/parser.dart
@@ -2836,9 +2836,9 @@
     }
 
     return FontExpression(_exprs.span,
-        size: fontSize!.font.size,
-        lineHeight: fontSize.font.lineHeight,
-        family: fontFamily!.font.family);
+        size: fontSize?.font.size,
+        lineHeight: fontSize?.font.lineHeight,
+        family: fontFamily?.font.family);
   }
 }
 

test/declaration_test.dart

diff --git a/test/declaration_test.dart b/test/declaration_test.dart
index 5dc24f6..6406efd 100644
--- a/test/declaration_test.dart
+++ b/test/declaration_test.dart
@@ -260,6 +260,33 @@
   expect(prettyPrint(stylesheet), generated);
 }
 
+void testNoValues() {
+  var errors = <Message>[];
+  final input = r'''
+.foo {
+  color: ;
+}
+.bar {
+  font:;
+  color: blue;
+}
+''';
+
+  final generated = r'''
+.foo {
+  color: ;
+}
+.bar {
+  font: ;
+  color: #00f;
+}''';
+
+  var stylesheet = parseCss(input, errors: errors, opts: simpleOptions);
+
+  expect(errors.isEmpty, true, reason: errors.toString());
+  expect(prettyPrint(stylesheet), generated);
+}
+
 void testUnicode() {
   var errors = <Message>[];
   final input = r'''
@@ -1435,6 +1462,7 @@
   test('Identifiers', testIdentifiers);
   test('Composites', testComposites);
   test('Units', testUnits);
+  test('No Values', testNoValues);
   test('Unicode', testUnicode);
   test('Newer CSS', testNewerCss);
   test('Media Queries', testMediaQueries);