IgnoreOnErrorResume(not tested)

src/R3/Operators/IgnoreElements.cs

@@ -4,21 +4,27 @@ public static partial class ObservableExtensions
 {
     public static Observable<T> IgnoreElements<T>(this Observable<T> source)
     {
-        return new IgnoreElements<T>(source);
+        return new IgnoreElements<T>(source, null);
+    }
+
+    public static Observable<T> IgnoreElements<T>(this Observable<T> source, Action<T> doOnNext)
+    {
+        return new IgnoreElements<T>(source, doOnNext);
     }
 }
 
-internal sealed class IgnoreElements<T>(Observable<T> source) : Observable<T>
+internal sealed class IgnoreElements<T>(Observable<T> source, Action<T>? doOnNext) : Observable<T>
 {
     protected override IDisposable SubscribeCore(Observer<T> observer)
     {
-        return source.Subscribe(new _IgnoreElements(observer));
+        return source.Subscribe(new _IgnoreElements(observer, doOnNext));
     }
 
-    sealed class _IgnoreElements(Observer<T> observer) : Observer<T>
+    sealed class _IgnoreElements(Observer<T> observer, Action<T>? doOnNext) : Observer<T>
     {
         protected override void OnNextCore(T value)
         {
+            doOnNext?.Invoke(value);
         }
 
         protected override void OnErrorResumeCore(Exception error)

src/R3/Operators/IgnoreOnErrorResume.cs

@@ -0,0 +1,40 @@
+namespace R3;
+
+public static partial class ObservableExtensions
+{
+    public static Observable<T> IgnoreOnErrorResume<T>(this Observable<T> source)
+    {
+        return new IgnoreOnErrorResume<T>(source, null);
+    }
+
+    public static Observable<T> IgnoreOnErrorResume<T>(this Observable<T> source, Action<Exception>? doOnErrorResume)
+    {
+        return new IgnoreOnErrorResume<T>(source, doOnErrorResume);
+    }
+}
+
+internal sealed class IgnoreOnErrorResume<T>(Observable<T> source, Action<Exception>? doOnErrorResume) : Observable<T>
+{
+    protected override IDisposable SubscribeCore(Observer<T> observer)
+    {
+        return source.Subscribe(new _IgnoreOnErrorResume(observer, doOnErrorResume));
+    }
+
+    sealed class _IgnoreOnErrorResume(Observer<T> observer, Action<Exception>? doOnErrorResume) : Observer<T>
+    {
+        protected override void OnNextCore(T value)
+        {
+            observer.OnNext(value);
+        }
+
+        protected override void OnErrorResumeCore(Exception error)
+        {
+            doOnErrorResume?.Invoke(error);
+        }
+
+        protected override void OnCompletedCore(Result result)
+        {
+            observer.OnCompleted(result);
+        }
+    }
+}

src/R3/Operators/_Operators.cs

@@ -12,6 +12,8 @@ public static partial class ObservableExtensions
 // TODO:not-tested:CombineLatest, Zip, ZipLatest, WithLatestFrom
 // Switch, Pairwise
 
+// IgnoreElements
+
 // Standard Query:
 // Distinct, DistinctBy, DistinctUntilChanged, Scan, DefaultIfEmpty