no whitespace for ya (#2831)

src/Discord.Net.Core/Entities/Interactions/MessageComponents/ComponentBuilder.cs

@@ -753,22 +753,22 @@ public ButtonBuilder WithDisabled(bool isDisabled)
         /// <exception cref="InvalidOperationException">A non-link button must contain a custom id</exception>
         public ButtonComponent Build()
         {
-            if (string.IsNullOrEmpty(Label) && Emote == null)
+            if (string.IsNullOrWhiteSpace(Label) && Emote == null)
                 throw new InvalidOperationException("A button must have an Emote or a label!");
 
-            if (!(string.IsNullOrEmpty(Url) ^ string.IsNullOrEmpty(CustomId)))
+            if (!(string.IsNullOrWhiteSpace(Url) ^ string.IsNullOrWhiteSpace(CustomId)))
                 throw new InvalidOperationException("A button must contain either a URL or a CustomId, but not both!");
 
             if (Style == 0)
                 throw new ArgumentException("A button must have a style.", nameof(Style));
 
             if (Style == ButtonStyle.Link)
             {
-                if (string.IsNullOrEmpty(Url))
+                if (string.IsNullOrWhiteSpace(Url))
                     throw new InvalidOperationException("Link buttons must have a link associated with them");
                 UrlValidation.ValidateButton(Url);
             }
-            else if (string.IsNullOrEmpty(CustomId))
+            else if (string.IsNullOrWhiteSpace(CustomId))
                 throw new InvalidOperationException("Non-link buttons must have a custom id associated with them");
 
             return new ButtonComponent(Style, Label, Emote, CustomId, Url, IsDisabled);