TypeError: Cannot read properties of null

[jbartula]

We constantly and at random get these errors:

2026-02-10 11:06:45.735 +01:00 [ERR] Unhandled exception in circuit 'ZtyCqLAZSwKF6KACUz0dQK9ZZbdfcGmd80_x1XQ1gPw'. Microsoft.JSInterop.JSException: Cannot read properties of null (reading 'getBoundingClientRect') TypeError: Cannot read properties of null (reading 'getBoundingClientRect') at Virtualiser2d.calculateViewRect (https://cenoplik.mil.local/_content/BlazorDatasheet/js/virtualise-2d.js:45:38) at https://cenoplik.mil.local/_framework/blazor.web.js:1:2900 at new Promise (<anonymous>) at w.beginInvokeJSFromDotNet (https://cenoplik.mil.local/_framework/blazor.web.js:1:2857) at vn._invokeClientMethod (https://cenoplik.mil.local/_framework/blazor.web.js:1:65751) at vn._processIncomingData (https://cenoplik.mil.local/_framework/blazor.web.js:1:63140) at Rn.onreceive (https://cenoplik.mil.local/_framework/blazor.web.js:1:56781) at WebSocket.<anonymous> (https://cenoplik.mil.local/_framework/blazor.web.js:1:80729) at Microsoft.JSInterop.JSRuntime.InvokeAsync[TValue](Int64 targetInstanceId, String identifier, Object[] args) at BlazorDatasheet.Virtualise.Virtualise2D.CalculateViewRect(ElementReference reference) at BlazorDatasheet.Virtualise.Virtualise2D.RefreshView() at BlazorDatasheet.Datasheet.RefreshView() at System.Threading.Tasks.Task.<>c.<ThrowAsync>b__128_0(Object state) at Microsoft.AspNetCore.Components.Rendering.RendererSynchronizationContext.PostAsync[TState](Task antecedent, Action1 callback, TState state)`

2026-02-10 11:07:45.457 +01:00 [ERR] Unhandled exception in circuit 'ZtyCqLAZSwKF6KACUz0dQK9ZZbdfcGmd80_x1XQ1gPw'. System.Threading.Tasks.TaskCanceledException: A task was canceled. at Microsoft.JSInterop.JSRuntime.InvokeAsync[TValue](Int64 targetInstanceId, String identifier, Object[] args) at BlazorDatasheet.Virtualise.Virtualise2D.CalculateViewRect(ElementReference reference) at BlazorDatasheet.Virtualise.Virtualise2D.RefreshView() at BlazorDatasheet.Datasheet.RefreshView() at System.Threading.Tasks.Task.<>c.<ThrowAsync>b__128_0(Object state) at Microsoft.AspNetCore.Components.Rendering.RendererSynchronizationContext.PostAsync[TState](Task antecedent, Action1 callback, TState state)`

2026-02-10 10:57:26.015 +01:00 [WRN] Unhandled exception rendering component: Object reference not set to an instance of an object. System.NullReferenceException: Object reference not set to an instance of an object. at BlazorDatasheet.Edit.EditorLayer.GetEditorSizeStyling() at BlazorDatasheet.Edit.EditorLayer.BuildRenderTree(RenderTreeBuilder __builder) at Microsoft.AspNetCore.Components.Rendering.ComponentState.RenderIntoBatch(RenderBatchBuilder batchBuilder, RenderFragment renderFragment, Exception& renderFragmentException)

[anmcgrath]

Hi @jbartula I'm hoping I've fixed this in #272 (release 0.9.4 on nuget.)

[jbartula]

We noticed a significant reduction of those errors. Thank you for the continous great work on this project!

However now, although much rarer, we get those errors:

Object name: 'Microsoft.JSInterop.DotNetObjectReference`1[[BlazorDatasheet.Virtualise.Virtualise2D, BlazorDatasheet, Version=0.9.4.0, Culture=neutral, PublicKeyToken=null]]'.
System.ObjectDisposedException: Cannot access a disposed object.
Object name: 'Microsoft.JSInterop.DotNetObjectReference`1[[BlazorDatasheet.Virtualise.Virtualise2D, BlazorDatasheet, Version=0.9.4.0, Culture=neutral, PublicKeyToken=null]]'.
   at Microsoft.JSInterop.JSRuntime.TrackObjectReference[TValue](DotNetObjectReference`1 dotNetObjectReference)
   at Microsoft.JSInterop.Infrastructure.DotNetObjectReferenceJsonConverter`1.Write(Utf8JsonWriter writer, DotNetObjectReference`1 value, JsonSerializerOptions options)
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.TryWriteAsObject(Utf8JsonWriter writer, Object value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonCollectionConverter`2.OnTryWrite(Utf8JsonWriter writer, TCollection value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.WriteCore(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.Metadata.JsonTypeInfo`1.Serialize(Utf8JsonWriter writer, T& rootValue, Object rootValueBoxed)
   at System.Text.Json.JsonSerializer.WriteString[TValue](TValue& value, JsonTypeInfo`1 jsonTypeInfo)
   at Microsoft.JSInterop.JSRuntime.InvokeAsync[TValue](Int64 targetInstanceId, String identifier, CancellationToken cancellationToken, Object[] args)
   at Microsoft.JSInterop.JSRuntime.InvokeAsync[TValue](Int64 targetInstanceId, String identifier, Object[] args)
   at Microsoft.JSInterop.JSObjectReferenceExtensions.InvokeVoidAsync(IJSObjectReference jsObjectReference, String identifier, Object[] args)
   at BlazorDatasheet.Virtualise.Virtualise2D.OnAfterRenderAsync(Boolean firstRender)
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.GetErrorHandledTask(Task taskToHandle, ComponentState owningComponentState)

or this one

Object name: 'Microsoft.JSInterop.DotNetObjectReference`1[[BlazorDatasheet.Services.WindowEventService, BlazorDatasheet, Version=0.9.4.0, Culture=neutral, PublicKeyToken=null]]'.
System.ObjectDisposedException: Cannot access a disposed object.
Object name: 'Microsoft.JSInterop.DotNetObjectReference`1[[BlazorDatasheet.Services.WindowEventService, BlazorDatasheet, Version=0.9.4.0, Culture=neutral, PublicKeyToken=null]]'.
   at Microsoft.JSInterop.JSRuntime.TrackObjectReference[TValue](DotNetObjectReference`1 dotNetObjectReference)
   at Microsoft.JSInterop.Infrastructure.DotNetObjectReferenceJsonConverter`1.Write(Utf8JsonWriter writer, DotNetObjectReference`1 value, JsonSerializerOptions options)
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.TryWriteAsObject(Utf8JsonWriter writer, Object value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonCollectionConverter`2.OnTryWrite(Utf8JsonWriter writer, TCollection value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.WriteCore(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.Metadata.JsonTypeInfo`1.Serialize(Utf8JsonWriter writer, T& rootValue, Object rootValueBoxed)
   at System.Text.Json.JsonSerializer.WriteString[TValue](TValue& value, JsonTypeInfo`1 jsonTypeInfo)
   at Microsoft.JSInterop.JSRuntime.InvokeAsync[TValue](Int64 targetInstanceId, String identifier, CancellationToken cancellationToken, Object[] args)
   at Microsoft.JSInterop.JSRuntime.InvokeAsync[TValue](Int64 targetInstanceId, String identifier, Object[] args)
   at BlazorDatasheet.Services.WindowEventService.CreateDotnetHelperIfNotExists()
   at BlazorDatasheet.Services.WindowEventService.RegisterMouseEvent(String eventType, Func`2 handler, Int32 throttleInMs)
   at BlazorDatasheet.Render.Headings.ColumnHeadingRenderer.OnAfterRenderAsync(Boolean firstRender)
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.GetErrorHandledTask(Task taskToHandle, ComponentState owningComponentState)

I would appreciate if you could look into those as well.