fix: missing check for FullName of selected branch while filtering branch in Statistic window (#2532)

Signed-off-by: leo <longshuang@msn.cn>

Author: love-linger

src/Commands/Statistics.cs

@@ -17,7 +17,7 @@ public Statistics(string repo, int max, Models.Branch specBranch)
                 .Append(max)
                 .Append(" --format=%ct$%aN±%aE ");
 
-            if (specBranch == null)
+            if (specBranch == null || string.IsNullOrEmpty(specBranch.FullName))
                 builder.Append("--branches --remotes");
             else
                 builder.Append(specBranch.FullName);