[VM/Service] Report the requested column in the error messages of CannotAddBreakpoint errors

TEST=CI

Change-Id: Ia74bd61ef0b166275d5828fb21cfa9c92c5f00cf
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/389280
Reviewed-by: Ben Konyi <[email protected]>
Commit-Queue: Derek Xu <[email protected]>

Author: derekxu16

pkg/vm_service/test/add_breakpoint_rpc_kernel_test.dart

@@ -139,7 +139,7 @@ final tests = <IsolateTest>[
       expect(e.code, RPCErrorKind.kCannotAddBreakpoint.code);
       expect(
         e.details,
-        'addBreakpoint: Cannot add breakpoint at line $LINE_A. Error occurred '
+        'addBreakpoint: Cannot add breakpoint at $LINE_A:37. Error occurred '
         'when resolving breakpoint location: No debuggable code where '
         'breakpoint was requested.',
       );

runtime/observatory/tests/service/add_breakpoint_rpc_kernel_test.dart

@@ -98,7 +98,7 @@ var tests = <IsolateTest>[
       expect(e.code, equals(ServerRpcException.kCannotAddBreakpoint));
       expect(
         e.message,
-        'addBreakpoint: Cannot add breakpoint at line $LINE_A. Error occurred '
+        'addBreakpoint: Cannot add breakpoint at $LINE_A:37. Error occurred '
         'when resolving breakpoint location: No debuggable code where '
         'breakpoint was requested.',
       );

runtime/vm/service.cc

@@ -4042,10 +4042,18 @@ static void AddBreakpointCommon(Thread* thread,
       Error::Handle(thread->isolate()->debugger()->SetBreakpointAtLineCol(
           script_uri, line, col, &bpt));
   if (!error.IsNull()) {
-    js->PrintError(kCannotAddBreakpoint,
-                   "%s: Cannot add breakpoint at line %s. Error occurred "
-                   "when resolving breakpoint location: %s.",
-                   js->method(), line_param, error.ToErrorCString());
+    if (col_param != nullptr) {
+      js->PrintError(
+          kCannotAddBreakpoint,
+          "%s: Cannot add breakpoint at %s:%s. Error occurred when resolving "
+          "breakpoint location: %s.",
+          js->method(), line_param, col_param, error.ToErrorCString());
+    } else {
+      js->PrintError(kCannotAddBreakpoint,
+                     "%s: Cannot add breakpoint at line %s. Error occurred "
+                     "when resolving breakpoint location: %s.",
+                     js->method(), line_param, error.ToErrorCString());
+    }
     return;
   }
   ASSERT(bpt != nullptr);