Handling errors gracefully prevents a single component crash from taking down the entire application. Blazor 6+ introduced Error Boundaries for this purpose.

ErrorBoundary Component

<ErrorBoundary>
    <ChildContent>
        <WeatherWidget />
    </ChildContent>
    <ErrorContent Context="ex">
        <p class="error">Failed: @ex.Message</p>
    </ErrorContent>
</ErrorBoundary>

Try-Catch in Lifecycle Methods

protected override async Task OnInitializedAsync()
{
    try
    {
        data = await Http.GetFromJsonAsync<List<Item>>("/api/items") ?? new();
    }
    catch (Exception ex)
    {
        errorMessage = ex.Message;
    }
}

Global Error UI

Blazor WASM shows a built-in error bar at the bottom when unhandled exceptions occur. Customize this in wwwroot/index.html by styling the #blazor-error-ui element.

Logging

Inject ILogger<T> and call _logger.LogError(ex, "message") for structured error logging.

Reference:

Wikipedia: Exception Handling

https://en.wikipedia.org/wiki/Exception_handling