Flutter engine not ready for debug yet

[aartbik]

984c407 introduced failure:

[ERROR:flutter/shell/common/shell.cc(182)] Dart Error: Unhandled exception:
Dummy exception to set exit code.
#0 _rootHandleUncaughtError.
(dart:async/zone.dart:1112:29)
#1 _microtaskLoop (dart:async/schedule_microtask.dart:41:21)
#2 _startMicrotaskLoop (dart:async/schedule_microtask.dart:50:5)
result 7353a2e5-2c85-41ea-af16-e8eb2581e731
7353a2e5-2c85-41ea-af16-e8eb2581e731 out/host_debug_unopt/engine_test.dill 0
00:00 �[32m+0�[0m: canvas APIs should not crash�[0m
../../third_party/dart/runtime/vm/object.cc: 9856: error: expected:
Dart::vm_snapshot_kind() == Snapshot::kFullAOT
Dumping native stack trace for thread 3414
[0x00000000029c5c2f] Unknown symbol
[0x00000000029c5c2f] Unknown symbol
-- End of DumpStackTrace

[aartbik]

@a-siva @rmacnak-google @aam @jason-simmons

[jason-simmons]

This failure happens when code in the dart:ui package that is built into the Flutter engine throws an AssertionError.

In the Dart VM, Script::Source returns null because the dart:ui script has a kind of kKernelTag. This results in an assertion failure in Script::GetSnippet, which is called while throwing the AssertionError.

Does the Flutter engine need to build the dart:ui Dart code in a different way?

[a-siva]

The code in Script::GetSnippet seems to assume that it will always find the source in JIT mode

const String& src = String::Handle(Source());
  if (src.IsNull()) {
    ASSERT(Dart::vm_snapshot_kind() == Snapshot::kFullAOT);
    return Symbols::OptimizedOut().raw();
  }

That assertion about snapshot being FullAOT seems incorrect