Handle V8 stack trace with no description line(s) (#2220)

Author: rakudrama

pkgs/stack_trace/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 1.12.2-dev
+
+* Relax parsing of V8 traces to allow a missing initial description.
+
 ## 1.12.1
 
 * Move to `dart-lang/tools` monorepo.

pkgs/stack_trace/lib/src/trace.dart

@@ -19,7 +19,10 @@ final _terseRegExp = RegExp(r'(-patch)?([/\\].*)?$');
 /// description of the exception that occurred. That description can be multiple
 /// lines, so we just look for any line other than the first that begins with
 /// three or four spaces and "at".
-final _v8Trace = RegExp(r'\n    ?at ');
+///
+/// Sometimes the first line is empty, and sometimes the empty line gets
+/// trimmed, so also accept a missing description line.
+final _v8Trace = RegExp(r'(?:^|\n)    ?at ');
 
 /// A RegExp to match indidual lines of V8's stack traces.
 ///
@@ -175,7 +178,6 @@ class Trace implements StackTrace {
       : this(
             trace
                 .split('\n')
-                .skip(1)
                 // It's possible that an Exception's description contains a line
                 // that looks like a V8 trace line, which will screw this up.
                 // Unfortunately, that's impossible to detect.

pkgs/stack_trace/pubspec.yaml

@@ -1,5 +1,5 @@
 name: stack_trace
-version: 1.12.1
+version: 1.12.2-wip
 description: A package for manipulating stack traces and printing them readably.
 repository: https://github.com/dart-lang/tools/tree/main/pkgs/stack_trace
 issue_tracker: https://github.com/dart-lang/tools/labels/package%3Astack_trace

pkgs/stack_trace/test/trace_test.dart

@@ -90,6 +90,22 @@ void main() {
       expect(
           trace.frames[2].uri, equals(Uri.parse('https://pub.dev/thing.js')));
       expect(trace.frames[2].member, equals('<fn>.zip.zap'));
+
+      // Missing description line
+      trace =
+          Trace.parse('    at Foo._bar (https://example.com/stuff.js:42:21)\n'
+              '    at https://example.com/stuff.js:0:2\n'
+              '    at (anonymous function).zip.zap '
+              '(https://pub.dev/thing.js:1:100)');
+
+      expect(trace.frames[0].uri,
+          equals(Uri.parse('https://example.com/stuff.js')));
+      expect(trace.frames[1].uri,
+          equals(Uri.parse('https://example.com/stuff.js')));
+      expect(trace.frames[1].member, equals('<fn>'));
+      expect(
+          trace.frames[2].uri, equals(Uri.parse('https://pub.dev/thing.js')));
+      expect(trace.frames[2].member, equals('<fn>.zip.zap'));
     });
 
     // JavaScriptCore traces are just like V8, except that it doesn't have a