fix: correctly check error on link

Author: Odonno

FirebaseAdmin/FirebaseAdmin.Tests/Messaging/MessageTest.cs

@@ -1605,7 +1605,7 @@ public void WebpushNotificationWithLinkUrl()
         }
 
         [Fact]
-        public void WebpushNotificationWithInvalidLinkUrl()
+        public void WebpushNotificationWithInvalidHttpLinkUrl()
         {
             var message = new Message()
             {
@@ -1627,6 +1627,29 @@ public void WebpushNotificationWithInvalidLinkUrl()
             Assert.Throws<ArgumentException>(() => message.CopyAndValidate());
         }
 
+        [Fact]
+        public void WebpushNotificationWithInvalidHttpsLinkUrl()
+        {
+            var message = new Message()
+            {
+                Topic = "test-topic",
+                Webpush = new WebpushConfig()
+                {
+                    Notification = new WebpushNotification()
+                    {
+                        Title = "title",
+                        Body = "body",
+                        Icon = "icon",
+                    },
+                    FcmOptions = new WebpushFcmOptions()
+                    {
+                        Link = "https whatever",
+                    },
+                },
+            };
+            Assert.Throws<ArgumentException>(() => message.CopyAndValidate());
+        }
+
         private void AssertJsonEquals(JObject expected, Message actual)
         {
             var json = NewtonsoftJsonSerializer.Instance.Serialize(actual.CopyAndValidate());

FirebaseAdmin/FirebaseAdmin/Messaging/WebpushFcmOptions.cs

@@ -40,9 +40,12 @@ internal WebpushFcmOptions CopyAndValidate()
                 Link = this.Link,
             };
 
-            if (copy.Link != null && Uri.IsWellFormedUriString(copy.Link, UriKind.Absolute) && !copy.Link.StartsWith("https"))
+            if (copy.Link != null)
             {
-                throw new ArgumentException("The link options should be a valid https url.");
+                if (!Uri.IsWellFormedUriString(copy.Link, UriKind.Absolute) || !copy.Link.StartsWith("https"))
+                {
+                    throw new ArgumentException("The link options should be a valid https url.");
+                }
             }
 
             return copy;