Bug and typos fix

Author: rosolko

WebDriverManager/DriverConfigs/Impl/ChromeConfig.cs

@@ -28,14 +28,15 @@ public string GetBinaryName()
 
         public string GetLatestVersion()
         {
-            var webRequest = WebRequest.Create(@"https://chromedriver.storage.googleapis.com/LATEST_RELEASE");
+            const string url = @"https://chromedriver.storage.googleapis.com/LATEST_RELEASE";
+            var webRequest = WebRequest.Create(url);
             using (var response = webRequest.GetResponse())
             {
                 using (var content = response.GetResponseStream())
                 {
                     if (content == null)
-                        throw new Exception(
-                            "Can't get content from URL", new Exception());
+                        throw new ArgumentNullException(
+                            $"Can't get content from URL: {url}");
                     using (var reader = new StreamReader(content))
                     {
                         var version = reader.ReadToEnd().Trim();

WebDriverManager/Services/Impl/VariableService.cs

@@ -14,7 +14,7 @@ protected void UpdatePath(string path)
         {
             const string name = "PATH";
             var pathVariable = Environment.GetEnvironmentVariable(name, EnvironmentVariableTarget.Process);
-            if (pathVariable == null) throw new Exception($"Can't get {name} variable");
+            if (pathVariable == null) throw new ArgumentNullException($"Can't get {name} variable");
             path = Path.GetDirectoryName(path);
             var newPathVariable = $"{path};{pathVariable}";
             if (!pathVariable.Contains(path))