Fix crash with empty fullname path

src/Core/FileTime.Core.Abstraction/Models/FullName.cs

@@ -7,11 +7,18 @@ public record FullName(string Path)
         var pathParts = Path.TrimEnd(Constants.SeparatorChar).Split(Constants.SeparatorChar);
         return pathParts.Length switch
         {
-            > 1 => new(string.Join(Constants.SeparatorChar, pathParts.SkipLast(1))),
+            > 1 => CreateSafe(string.Join(Constants.SeparatorChar, pathParts.SkipLast(1))),
             _ => null
         };
     }
 
+    public static FullName? CreateSafe(string? path)
+    {
+        if (string.IsNullOrWhiteSpace(path))
+            return null;
+        return new(path);
+    }
+
     public string GetName()
         => Path.Split(Constants.SeparatorChar).Last();