Clean up stack traces on build() failure

[matanlurey]

Here is a stack trace for when the output fails dartfmt:

[INFO] Build: Running build...
[SEVERE] runBuilder: Error formatting generated source code for 112din/lib/src/schema/structures/channel.dartwhich was output to lib/src/schema/structures/channel.g.dart.
This may indicate an issue in the generated code or in the formatter.
Please check the generated code and file an issue on source_gen if appropriate.
Could not format because the source could not be parsed:

line 8, column 37: A non-redirecting 'factory' constructor must have a body.
class _$Channel implements Channel {factory _$Channel.fromJson(Map<String,Object> json);_$Channel(build);@override dynamic noSuchMethod(i) => super.noSuchMethod(i); }class _$ChannelBuilder { }
                                    ^^^^^^^
#0      ErrorListener.throwIfErrors (package:dart_style/src/error_listener.dart:23:5)
#1      DartFormatter.formatSource (package:dart_style/src/dart_formatter.dart:128:19)
#2      DartFormatter.format (package:dart_style/src/dart_formatter.dart:65:12)
#3      _Builder._generateForLibrary (package:source_gen/src/builder.dart:127:36)
<asynchronous suspension>
#4      _Builder.build (package:source_gen/src/builder.dart:69:11)
<asynchronous suspension>
#5      runBuilder.buildForInput (package:build/src/generate/run_builder.dart:43:21)
<asynchronous suspension>
#6      MappedListIterable.elementAt (dart:_internal/iterable.dart:413)
#7      ListIterator.moveNext (dart:_internal/iterable.dart:342)
#8      Future.wait (dart:async/future.dart:355)
#9      runBuilder.<anonymous closure> (package:build/src/generate/run_builder.dart:49:31)
#10     _rootRun (dart:async/zone.dart:1120)
#11     _CustomZone.run (dart:async/zone.dart:1001)
#12     runZoned (dart:async/zone.dart:1467)
#13     scopeLog (package:build/src/builder/logging.dart:12:38)
#14     runBuilder (package:build/src/generate/run_builder.dart:49:9)
<asynchronous suspension>
#15     BuildImpl._runBuilder (package:build_runner/src/generate/build_impl.dart:229:13)
<asynchronous suspension>
#16     BuildImpl._runPhases (package:build_runner/src/generate/build_impl.dart:181:14)
<asynchronous suspension>
#17     logWithTime (package:build_runner/src/logging/logging.dart:19:28)
<asynchronous suspension>
#18     BuildImpl._safeBuild.<anonymous closure> (package:build_runner/src/generate/build_impl.dart:102:26)
<asynchronous suspension>
#19     Chain.capture.<anonymous closure> (package:stack_trace/src/chain.dart:93:24)
#20     _rootRun (dart:async/zone.dart:1120)
#21     _CustomZone.run (dart:async/zone.dart:1001)
#22     runZoned (dart:async/zone.dart:1467)
#23     Chain.capture (package:stack_trace/src/chain.dart:91:12)
#24     BuildImpl._safeBuild (package:build_runner/src/generate/build_impl.dart:100:11)
#25     BuildImpl.run (package:build_runner/src/generate/build_impl.dart:75:24)
<asynchronous suspension>
#26     BuildImpl.create (package:build_runner/src/generate/build_impl.dart:68:37)
<asynchronous suspension>
#27     singleBuild (package:build_runner/src/generate/build_impl.dart:33:27)
<asynchronous suspension>
#28     build (package:build_runner/src/generate/build.dart:63:22)
<asynchronous suspension>
#29     main (file:///Users/matan/git/din/tool/generators/api.dart:18:9)
<asynchronous suspension>
#30     _startIsolate.<anonymous closure> (dart:isolate-patch/isolate_patch.dart:263)
#31     _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:151)

We should probably be using .terse to clean this up, potentially also removing pkg/build.

[matanlurey]

Matan is going to take a shot here!