[dotnet] Handle nullability on WebElement

[RenderMichael]

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Annotate nullability on helper interfaces on WebElement. Refactor WebElement to minimize diffs when nullability is fully annotated on the type.

Motivation and Context

Contributes to #14640

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• I have read the contributing document.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

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PR Type

Enhancement, Bug fix

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Description

• Enabled nullability annotations for WebElement and related interfaces.

• Refactored WebElement class to improve null safety and readability.

• Simplified and optimized code in WebElementFactory.

• Replaced redundant methods and improved exception handling.

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Changes walkthrough 📝

Relevant files

Enhancement

ILocatable.cs Add nullability annotations to `ILocatable`                            dotnet/src/webdriver/ILocatable.cs Enabled nullability annotations. No functional changes, only metadata updates. +2/-0      ITakesScreenshot.cs Add nullability annotations to `ITakesScreenshot`                dotnet/src/webdriver/ITakesScreenshot.cs Enabled nullability annotations. No functional changes, only metadata updates. +2/-0      WebElement.cs Refactor `WebElement` and enable nullability                          dotnet/src/webdriver/WebElement.cs Enabled nullability annotations. Refactored WebElement to use Id property instead of elementId field. Simplified methods by removing redundant checks and improving readability. Improved exception handling and code consistency. +71/-100 WebElementFactory.cs Refactor `WebElementFactory` and enable nullability            dotnet/src/webdriver/WebElementFactory.cs Enabled nullability annotations. Simplified GetElementId method and removed redundant TryGetElementPropertyName. Improved exception handling for null or invalid inputs. +22/-30

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PR Reviewer Guide 🔍

Here are some key observations to aid the review process:

⏱️ Estimated effort to review: 3 🔵🔵🔵⚪⚪

🧪 No relevant tests

🔒 No security concerns identified

⚡ Recommended focus areas for review Null Safety The GetDomAttribute and GetDomProperty methods return ToString() on potentially null values without proper null checks, which could cause NullReferenceException. return commandResponse.Value?.ToString(); Error Handling The ContainsElementReference method throws ArgumentNullException but returns false would be more appropriate for a boolean check method. if (elementDictionary == null) { throw new ArgumentNullException(nameof(elementDictionary), "The dictionary containing the element reference cannot be null"); } return elementDictionary.ContainsKey(WebElement.ElementReferencePropertyName); }

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PR Code Suggestions ✨

Explore these optional code suggestions:

Category	Suggestion	Score
Possible issue	Prevent null reference exception Add null check for commandResponse.Value before calling ToString() to prevent potential NullReferenceException. dotnet/src/webdriver/WebElement.cs [78-79] Response commandResponse = this.Execute(DriverCommand.GetElementTagName, parameters); -return commandResponse.Value.ToString(); +return commandResponse.Value?.ToString() ?? string.Empty; Apply this suggestion Suggestion importance[1-10]: 8 Why: The suggestion adds important null checking to prevent NullReferenceException when accessing commandResponse.Value, which could be null. This is a critical defensive programming practice.	8
	Handle invalid response format Add null check for scriptResponse before casting to Dictionary to prevent potential InvalidCastException. dotnet/src/webdriver/WebElement.cs [210-211] object scriptResponse = this.driver.ExecuteScript("var rect = arguments[0].getBoundingClientRect(); return {'x': rect.left, 'y': rect.top};", this); -Dictionary<string, object> rawLocation = (Dictionary<string, object>)scriptResponse; +if (scriptResponse is not Dictionary<string, object> rawLocation) +{ + throw new WebDriverException("Failed to get element location - invalid response format"); +} Apply this suggestion Suggestion importance[1-10]: 8 Why: The suggestion improves error handling by properly checking the response type and providing a clear error message when the format is invalid, preventing potential runtime exceptions.	8

[RenderMichael]

Failures are not related to changes in this PR:

//java/test/org/openqa/selenium/mobile:NetworkConnectionTest
//java/test/org/openqa/selenium/remote:RemoteWebDriverScreenshotTest
//java/test/org/openqa/selenium/remote:RemoteWebDriverScreenshotTest-firefox-beta