Fix a new strong mode error. (#13)

Closes #12
diff --git a/CHANGELOG.md b/CHANGELOG.md
index db3d320..3ba6f6e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+# 1.3.1
+
+* Fix a new strong mode error.
+
 # 1.3.0
 
 * Make the `VersionUnion` class public. This was previously used internally to
diff --git a/lib/src/version_range.dart b/lib/src/version_range.dart
index ffa50ab..861ae46 100644
--- a/lib/src/version_range.dart
+++ b/lib/src/version_range.dart
@@ -321,7 +321,7 @@
     } else if (other is VersionRange) {
       if (!allowsAny(other)) return this;
 
-      VersionConstraint before;
+      VersionRange before;
       if (!allowsLower(this, other)) {
         before = VersionConstraint.empty;
       } else if (min == other.min) {
@@ -334,7 +334,7 @@
             includeMin: includeMin, includeMax: !other.includeMin);
       }
 
-      VersionConstraint after;
+      VersionRange after;
       if (!allowsHigher(this, other)) {
         after = VersionConstraint.empty;
       } else if (max == other.max) {
diff --git a/pubspec.yaml b/pubspec.yaml
index 531ace6..1712f6e 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,5 +1,5 @@
 name: pub_semver
-version: 1.3.0
+version: 1.3.1
 author: Dart Team <misc@dartlang.org>
 description: >
  Versions and version constraints implementing pub's versioning policy. This