Fixed compiler warnings

Author: sakno

src/DotNext/Net/Http/HttpEndPoint.cs

@@ -168,7 +168,7 @@ bool ISpanFormattable.TryFormat(Span<char> destination, out int charsWritten, Re
                                   && writer.TryFormat(Port, format, provider)
                                   && writer.TryAdd('/'))
             ? writer.WrittenCount
-            : default;
+            : 0;
 
         return success;
     }
@@ -185,7 +185,7 @@ bool IUtf8SpanFormattable.TryFormat(Span<byte> destination, out int bytesWritten
                                   && writer.TryFormat(Port, format, provider)
                                   && writer.TryAdd((byte)'/'))
             ? writer.WrittenCount
-            : default;
+            : 0;
 
         return success;
     }