Unhandled exception:
Unsupported operation: serialization of generic DartType: UnknownType(?) (UnknownType)
#0 BinaryPrinter.defaultDartType (package:kernel/binary/ast_to_binary.dart:2231:5)
#1 UnknownType.accept (package:front_end/src/fasta/type_inference/type_schema.dart:82:14)
#2 BinaryPrinter.writeNode (package:kernel/binary/ast_to_binary.dart:382:10)
#3 BinaryPrinter.writeNodeList (package:kernel/binary/ast_to_binary.dart:292:7)
#4 BinaryPrinter.visitInterfaceType (package:kernel/binary/ast_to_binary.dart:2069:7)
#5 InterfaceType.accept (package:kernel/ast.dart:7504:42)
#6 BinaryPrinter.writeNode (package:kernel/binary/ast_to_binary.dart:382:10)
#7 BinaryPrinter.visitFutureOrType (package:kernel/binary/ast_to_binary.dart:2090:5)
#8 FutureOrType.accept (package:kernel/ast.dart:7903:42)
#9 BinaryPrinter.writeNode (package:kernel/binary/ast_to_binary.dart:382:10)
#10 BinaryPrinter.visitAsExpression (package:kernel/binary/ast_to_binary.dart:1616:5)
#11 AsExpression.accept (package:kernel/ast.dart:4913:44)
#12 BinaryPrinter.writeNode (package:kernel/binary/ast_to_binary.dart:382:10)
#13 BinaryPrinter.visitVariableSet (package:kernel/binary/ast_to_binary.dart:1368:7)
#14 VariableSet.accept (package:kernel/ast.dart:3144:44)
#15 BinaryPrinter.writeNode (package:kernel/binary/ast_to_binary.dart:382:10)
#16 BinaryPrinter.visitExpressionStatement
(package:kernel/binary/ast_to_binary.dart:1795:5)
#17 ExpressionStatement.accept (package:kernel/ast.dart:5784:43)
#18 BinaryPrinter.writeNode (package:kernel/binary/ast_to_binary.dart:382:10)
#19 BinaryPrinter.writeNodeList (package:kernel/binary/ast_to_binary.dart:292:7)
#20 BinaryPrinter.visitBlock (package:kernel/binary/ast_to_binary.dart:1803:5)
#21 Block.accept (package:kernel/ast.dart:5823:43)
#22 BinaryPrinter.writeNode (package:kernel/binary/ast_to_binary.dart:382:10)
#23 BinaryPrinter.visitLabeledStatement (package:kernel/binary/ast_to_binary.dart:1837:5)
#24 LabeledStatement.accept (package:kernel/ast.dart:5984:43)
#25 BinaryPrinter.writeNode (package:kernel/binary/ast_to_binary.dart:382:10)
#26 BinaryPrinter.writeNodeList (package:kernel/binary/ast_to_binary.dart:292:7)
#27 BinaryPrinter.visitBlock (package:kernel/binary/ast_to_binary.dart:1803:5)
#28 Block.accept (package:kernel/ast.dart:5823:43)
#29 BinaryPrinter.writeNode (package:kernel/binary/ast_to_binary.dart:382:10)
#30 BinaryPrinter.visitTryCatch (package:kernel/binary/ast_to_binary.dart:1954:5)
#31 TryCatch.accept (package:kernel/ast.dart:6532:43)
#32 BinaryPrinter.writeNode (package:kernel/binary/ast_to_binary.dart:382:10)
#33 BinaryPrinter.writeOptionalNode (package:kernel/binary/ast_to_binary.dart:475:7)
#34 BinaryPrinter.visitFunctionNode (package:kernel/binary/ast_to_binary.dart:1327:5)
#35 FunctionNode.accept (package:kernel/ast.dart:2909:38)
#36 BinaryPrinter.writeFunctionNode (package:kernel/binary/ast_to_binary.dart:389:10)
#37 BinaryPrinter.visitFunctionDeclaration
(package:kernel/binary/ast_to_binary.dart:2030:5)
#38 FunctionDeclaration.accept (package:kernel/ast.dart:6988:43)
#39 BinaryPrinter.writeNode (package:kernel/binary/ast_to_binary.dart:382:10)
#40 BinaryPrinter.writeNodeList (package:kernel/binary/ast_to_binary.dart:292:7)
#41 BinaryPrinter.visitBlock (package:kernel/binary/ast_to_binary.dart:1803:5)
#42 Block.accept (package:kernel/ast.dart:5823:43)
#43 BinaryPrinter.writeNode (package:kernel/binary/ast_to_binary.dart:382:10)
#44 BinaryPrinter.writeOptionalNode (package:kernel/binary/ast_to_binary.dart:475:7)
#45 BinaryPrinter.visitFunctionNode (package:kernel/binary/ast_to_binary.dart:1327:5)
#46 FunctionNode.accept (package:kernel/ast.dart:2909:38)
#47 BinaryPrinter.writeFunctionNode (package:kernel/binary/ast_to_binary.dart:389:10)
#48 BinaryPrinter.visitFunctionExpression
(package:kernel/binary/ast_to_binary.dart:1742:5)
#49 FunctionExpression.accept (package:kernel/ast.dart:5535:44)
#50 BinaryPrinter.writeNode (package:kernel/binary/ast_to_binary.dart:382:10)
#51 BinaryPrinter.visitNamedExpression (package:kernel/binary/ast_to_binary.dart:1503:5)
#52 NamedExpression.accept (package:kernel/ast.dart:3813:38)
#53 BinaryPrinter.writeNode (package:kernel/binary/ast_to_binary.dart:382:10)
#54 BinaryPrinter.writeNodeList (package:kernel/binary/ast_to_binary.dart:292:7)
#55 BinaryPrinter.visitArguments (package:kernel/binary/ast_to_binary.dart:1497:5)
#56 Arguments.accept (package:kernel/ast.dart:3753:38)
#57 BinaryPrinter.writeArgumentsNode (package:kernel/binary/ast_to_binary.dart:396:10)
#58 BinaryPrinter.visitConstructorInvocation
(package:kernel/binary/ast_to_binary.dart:1489:5)
#59 ConstructorInvocation.accept (package:kernel/ast.dart:4154:44)
#60 BinaryPrinter.writeNode (package:kernel/binary/ast_to_binary.dart:382:10)
#61 BinaryPrinter.visitNamedExpression (package:kernel/binary/ast_to_binary.dart:1503:5)
#62 NamedExpression.accept (package:kernel/ast.dart:3813:38)
#63 BinaryPrinter.writeNode (package:kernel/binary/ast_to_binary.dart:382:10)
#64 BinaryPrinter.writeNodeList (package:kernel/binary/ast_to_binary.dart:292:7)
#65 BinaryPrinter.visitArguments (package:kernel/binary/ast_to_binary.dart:1497:5)
#66 Arguments.accept (package:kernel/ast.dart:3753:38)
#67 BinaryPrinter.writeArgumentsNode (package:kernel/binary/ast_to_binary.dart:396:10)
#68 BinaryPrinter.visitConstructorInvocation
(package:kernel/binary/ast_to_binary.dart:1489:5)
#69 ConstructorInvocation.accept (package:kernel/ast.dart:4154:44)
#70 BinaryPrinter.writeNode (package:kernel/binary/ast_to_binary.dart:382:10)
#71 BinaryPrinter.writeOptionalNode (package:kernel/binary/ast_to_binary.dart:475:7)
#72 BinaryPrinter.visitReturnStatement (package:kernel/binary/ast_to_binary.dart:1944:5)
#73 ReturnStatement.accept (package:kernel/ast.dart:6491:43)
#74 BinaryPrinter.writeNode (package:kernel/binary/ast_to_binary.dart:382:10)
#75 BinaryPrinter.writeNodeList (package:kernel/binary/ast_to_binary.dart:292:7)
#76 BinaryPrinter.visitBlock (package:kernel/binary/ast_to_binary.dart:1803:5)
#77 Block.accept (package:kernel/ast.dart:5823:43)
#78 BinaryPrinter.writeNode (package:kernel/binary/ast_to_binary.dart:382:10)
#79 BinaryPrinter.writeOptionalNode (package:kernel/binary/ast_to_binary.dart:475:7)
#80 BinaryPrinter.visitFunctionNode (package:kernel/binary/ast_to_binary.dart:1327:5)
#81 FunctionNode.accept (package:kernel/ast.dart:2909:38)
#82 BinaryPrinter.writeFunctionNode (package:kernel/binary/ast_to_binary.dart:389:10)
#83 BinaryPrinter.writeOptionalFunctionNode
(package:kernel/binary/ast_to_binary.dart:484:7)
#84 BinaryPrinter.visitProcedure (package:kernel/binary/ast_to_binary.dart:1203:5)
#85 Procedure.accept (package:kernel/ast.dart:2400:40)
#86 BinaryPrinter.writeProcedureNode (package:kernel/binary/ast_to_binary.dart:410:10)
#87 BinaryPrinter.writeProcedureNodeList (package:kernel/binary/ast_to_binary.dart:301:7)
#88 BinaryPrinter.visitClass (package:kernel/binary/ast_to_binary.dart:1131:5)
#89 Class.accept (package:kernel/ast.dart:1379:38)
#90 BinaryPrinter.writeClassNode (package:kernel/binary/ast_to_binary.dart:424:10)
#91 BinaryPrinter.writeClassNodeList (package:kernel/binary/ast_to_binary.dart:319:7)
#92 BinaryPrinter.visitLibrary (package:kernel/binary/ast_to_binary.dart:961:5)
#93 Library.accept (package:kernel/ast.dart:607:38)
#94 BinaryPrinter.writeLibraryNode (package:kernel/binary/ast_to_binary.dart:403:10)
#95 BinaryPrinter.writeLibraries (package:kernel/binary/ast_to_binary.dart:710:9)
#96 BinaryPrinter.writeComponentFile.
(package:kernel/binary/ast_to_binary.dart:553:7)
#97 Timeline.timeSync (dart:developer/timeline.dart:163:22)
#98 BinaryPrinter.writeComponentFile (package:kernel/binary/ast_to_binary.dart:536:14)
#99 IncrementalSerializer.serialize
(package:front_end/src/fasta/incremental_serializer.dart:308:13)
#100 IncrementalSerializer.writePackagesToSinkAndTrimComponent
(package:front_end/src/fasta/incremental_serializer.dart:159:24)
#101 FrontendCompiler.writeDillFile (package:frontend_server/frontend_server.dart:747:31)
#102 FrontendCompiler.compile (package:frontend_server/frontend_server.dart:564:13)

#103 _FlutterFrontendCompiler.compile (package:flutter_frontend_server/server.dart:43:22)
#104 listenAndCompile.
(package:frontend_server/frontend_server.dart:1201:26)
#105 _RootZone.runUnaryGuarded (dart:async/zone.dart:1384:10)
#106 _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:357:11)
#107 _BufferingStreamSubscription._add (dart:async/stream_impl.dart:285:7)
#108 _SinkTransformerStreamSubscription._add (dart:async/stream_transformers.dart:69:11)
#109 _EventSinkWrapper.add (dart:async/stream_transformers.dart:15:11)
#110 _StringAdapterSink.add (dart:convert/string_conversion.dart:238:11)
#111 _LineSplitterSink._addLines (dart:convert/line_splitter.dart:155:13)
#112 _LineSplitterSink.addSlice (dart:convert/line_splitter.dart:130:5)
#113 StringConversionSinkMixin.add (dart:convert/string_conversion.dart:163:5)
#114 _SinkTransformerStreamSubscription._handleData
(dart:async/stream_transformers.dart:121:24)
#115 _RootZone.runUnaryGuarded (dart:async/zone.dart:1384:10)
#116 _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:357:11)
#117 _BufferingStreamSubscription._add (dart:async/stream_impl.dart:285:7)
#118 _SinkTransformerStreamSubscription._add (dart:async/stream_transformers.dart:69:11)
#119 _EventSinkWrapper.add (dart:async/stream_transformers.dart:15:11)
#120 _StringAdapterSink.add (dart:convert/string_conversion.dart:238:11)
#121 _StringAdapterSink.addSlice (dart:convert/string_conversion.dart:243:7)
#122 _Utf8ConversionSink.addSlice (dart:convert/string_conversion.dart:317:20)
#123 _Utf8ConversionSink.add (dart:convert/string_conversion.dart:310:5)
#124 _ConverterStreamEventSink.add (dart:convert/chunked_conversion.dart:72:18)
#125 _SinkTransformerStreamSubscription._handleData
(dart:async/stream_transformers.dart:121:24)
#126 _RootZone.runUnaryGuarded (dart:async/zone.dart:1384:10)
#127 _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:357:11)
#128 _BufferingStreamSubscription._add (dart:async/stream_impl.dart:285:7)
#129 _SyncStreamControllerDispatch._sendData (dart:async/stream_controller.dart:808:19)
#130 _StreamController._add (dart:async/stream_controller.dart:682:7)
#131 _StreamController.add (dart:async/stream_controller.dart:624:5)
#132 _Socket._onData (dart:io-patch/socket_patch.dart:2020:41)
#133 _RootZone.runUnaryGuarded (dart:async/zone.dart:1384:10)
#134 _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:357:11)
#135 _BufferingStreamSubscription._add (dart:async/stream_impl.dart:285:7)
#136 _SyncStreamControllerDispatch._sendData (dart:async/stream_controller.dart:808:19)
#137 _StreamController._add (dart:async/stream_controller.dart:682:7)
#138 _StreamController.add (dart:async/stream_controller.dart:624:5)
#139 new _RawSocket. (dart:io-patch/socket_patch.dart:1556:33)
#140 _NativeSocket.issueReadEvent.issue (dart:io-patch/socket_patch.dart:1052:14)
#141 _microtaskLoop (dart:async/schedule_microtask.dart:41:21)
#142 _startMicrotaskLoop (dart:async/schedule_microtask.dart:50:5)
#143 _runPendingImmediateCallback (dart:isolate-patch/isolate_patch.dart:118:13)
#144 _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:169:5)
the Dart compiler exited unexpectedly.
the Dart compiler exited unexpectedly.