Fix violations of body_might_complete_normally_catch_error hint

by converting the Future to void, seeing as the return value is not used anyway

Change-Id: Ifb4fdc6f909bc0432427b0e58d59eb10a1c7a5cd
Tested: only CI.
Bug: #49215
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/269303
Reviewed-by: Daco Harkes <[email protected]>
Commit-Queue: Oleh Prypin <[email protected]>

Author: oprypin

runtime/observatory/lib/src/elements/debugger.dart

@@ -2118,7 +2118,7 @@ class DebuggerPageElement extends CustomElement implements Renderable {
         app.vm.listenEventStream(S.VM.kStdoutStream, _debugger.onStdout);
     if (_stdoutSubscriptionFuture != null) {
       // TODO(turnidge): How do we want to handle this in general?
-      _stdoutSubscriptionFuture!.catchError((e, st) {
+      _stdoutSubscriptionFuture!.then((_) {}, onError: (e, st) {
         Logger.root.info('Failed to subscribe to stdout: $e\n$st\n');
         _stdoutSubscriptionFuture = null;
       });
@@ -2127,7 +2127,7 @@ class DebuggerPageElement extends CustomElement implements Renderable {
         app.vm.listenEventStream(S.VM.kStderrStream, _debugger.onStderr);
     if (_stderrSubscriptionFuture != null) {
       // TODO(turnidge): How do we want to handle this in general?
-      _stderrSubscriptionFuture!.catchError((e, st) {
+      _stderrSubscriptionFuture!.then((_) {}, onError: (e, st) {
         Logger.root.info('Failed to subscribe to stderr: $e\n$st\n');
         _stderrSubscriptionFuture = null;
       });

runtime/observatory/lib/src/elements/script_inset.dart

@@ -809,9 +809,8 @@ class ScriptInsetElement extends CustomElement implements Renderable {
       busy = true;
       if (line.breakpoints == null) {
         // No breakpoint.  Add it.
-        line.script.isolate!
-            .addBreakpoint(line.script, line.line)
-            .catchError((e, st) {
+        line.script.isolate!.addBreakpoint(line.script, line.line).then((_) {},
+            onError: (e, st) {
           if (e is! S.ServerRpcException ||
               (e as S.ServerRpcException).code !=
                   S.ServerRpcException.kCannotAddBreakpoint) {

runtime/observatory/lib/src/service/object.dart

@@ -805,7 +805,7 @@ abstract class VM extends ServiceObjectOwner implements M.VM {
           _buildIsolateList();
 
           // Eagerly load the isolate.
-          isolate.load().catchError((e, stack) {
+          isolate.load().then((_) {}, onError: (e, stack) {
             Logger.root.info('Eagerly loading an isolate failed: $e\n$stack');
           });
         } else {
@@ -823,7 +823,7 @@ abstract class VM extends ServiceObjectOwner implements M.VM {
           _buildIsolateGroupList();
 
           // Eagerly load the isolate.
-          isolateGroup.load().catchError((e, stack) {
+          isolateGroup.load().then((_) {}, onError: (e, stack) {
             Logger.root
                 .info('Eagerly loading an isolate group failed: $e\n$stack');
           });
@@ -1062,9 +1062,9 @@ abstract class VM extends ServiceObjectOwner implements M.VM {
 
   // Reload all isolates.
   Future reloadIsolates() {
-    var reloads = <Future>[];
+    var reloads = <Future<void>>[];
     for (var isolate in isolates) {
-      var reload = isolate.reload().catchError((e) {
+      var reload = isolate.reload().then((_) {}, onError: (e) {
         Logger.root.info('Bulk reloading of isolates failed: $e');
       });
       reloads.add(reload);