Rework error handling in the service protocol and in Observatory.

runtime/vm/service_test.cc

Index: runtime/vm/service_test.cc
diff --git a/runtime/vm/service_test.cc b/runtime/vm/service_test.cc
index fd3ec237f7f9267dfd3572cbac09bf71349c67be..7751eceb2d9c4ad488d3614d5012a060c72f1dbc 100644
--- a/runtime/vm/service_test.cc
+++ b/runtime/vm/service_test.cc
@@ -160,7 +160,7 @@ TEST_CASE(Service_Code) {
       Eval(lib, "[0, port, '0', 'getObject', ['objectId'], ['code/0']]");
   Service::HandleIsolateMessage(isolate, service_msg);
   handler.HandleNextMessage();
-  EXPECT_SUBSTRING("\"type\":\"Error\"", handler.msg());
+  EXPECT_SUBSTRING("\"error\"", handler.msg());
 
   // The following test checks that a code object can be found only
   // at compile_timestamp()-code.EntryPoint().
@@ -190,7 +190,7 @@ TEST_CASE(Service_Code) {
                       address);
   Service::HandleIsolateMessage(isolate, service_msg);
   handler.HandleNextMessage();
-  EXPECT_SUBSTRING("\"type\":\"Error\"", handler.msg());
+  EXPECT_SUBSTRING("\"error\"", handler.msg());
 
   // Request code object at (compile_timestamp - 1)-code.EntryPoint()
   // Expect this to fail because the timestamp is wrong.
@@ -201,7 +201,7 @@ TEST_CASE(Service_Code) {
                       address);
   Service::HandleIsolateMessage(isolate, service_msg);
   handler.HandleNextMessage();
-  EXPECT_SUBSTRING("\"type\":\"Error\"", handler.msg());
+  EXPECT_SUBSTRING("\"error\"", handler.msg());
 
   // Request native code at address. Expect the null code object back.
   address = last;
@@ -220,7 +220,7 @@ TEST_CASE(Service_Code) {
                       address);
   Service::HandleIsolateMessage(isolate, service_msg);
   handler.HandleNextMessage();
-  EXPECT_SUBSTRING("\"type\":\"Error\"", handler.msg());
+  EXPECT_SUBSTRING("\"error\"", handler.msg());
 }
 
 
@@ -575,7 +575,7 @@ TEST_CASE(Service_Profile) {
   Service::HandleIsolateMessage(isolate, service_msg);
   handler.HandleNextMessage();
   // Expect error (tags required).
-  EXPECT_SUBSTRING("\"type\":\"Error\"", handler.msg());
+  EXPECT_SUBSTRING("\"error\"", handler.msg());
 
   service_msg =
       Eval(lib, "[0, port, '0', 'getCpuProfile', ['tags'], ['None']]");
@@ -589,7 +589,7 @@ TEST_CASE(Service_Profile) {
   Service::HandleIsolateMessage(isolate, service_msg);
   handler.HandleNextMessage();
   // Expect error.
-  EXPECT_SUBSTRING("\"type\":\"Error\"", handler.msg());
+  EXPECT_SUBSTRING("\"error\"", handler.msg());
 }
 
 #endif  // !defined(TARGET_ARCH_ARM64)