Non-nullable model fields in task/models.dart (#8469)

Author: isoos

app/lib/search/backend.dart

@@ -240,9 +240,7 @@ class SearchBackend {
       ..filter('finished >=', updatedThreshold)
       ..order('-finished');
     await for (final s in q3.run()) {
-      if (s.finished != null) {
-        addResult(s.package, s.finished!);
-      }
+      addResult(s.package, s.finished);
     }
 
     return results;

app/lib/task/backend.dart

@@ -834,7 +834,7 @@ class TaskBackend {
         return await _loadTaskResultIndex(
           package: package,
           version: version,
-          runtimeVersion: status.runtimeVersion ?? runtimeVersion,
+          runtimeVersion: status.runtimeVersion,
         );
       },
     );
@@ -986,9 +986,6 @@ class TaskBackend {
     final data = await gzippedTaskResult(package, version, 'log.txt');
     if (data == null) {
       final status = await packageStatus(package);
-      if (status.runtimeVersion == null) {
-        return 'no log - no tracking information';
-      }
       final v = status.versions[version];
       if (v == null) {
         return 'no log - version is not tracked';

app/lib/task/models.dart

@@ -132,9 +132,8 @@ class PackageState extends db.ExpandoModel<String> {
   DateTime? lastDependencyChanged;
 
   /// The last time the a worker completed with a failure or success.
-  /// TODO: make it `required: true` after the acceptable runtimes are after 2023.08.18.
-  @db.DateTimeProperty(required: false, indexed: true)
-  DateTime? finished;
+  @db.DateTimeProperty(required: true, indexed: true)
+  DateTime finished = initialTimestamp;
 
   /// Derive [pendingAt] using [versions] and [lastDependencyChanged].
   ///
@@ -370,8 +369,7 @@ class PackageVersionStateMapProperty extends db.Property {
 /// Status for a package.
 @JsonSerializable()
 class PackageStateInfo {
-  // TODO: make this non-nullable after we are past 2023.08.18 as accepted runtimeVersion.
-  final String? runtimeVersion;
+  final String runtimeVersion;
   final String package;
 
   /// Status for versions.