Properly close archive files after validating them

src/util.cr

@@ -95,12 +95,16 @@ def compare_alphanumerically(a : String, b : String)
 end
 
 def validate_archive(path : String) : Exception?
-  file = ArchiveFile.new path
+  file = nil
-  file.check
+  begin
-  file.close
+    file = ArchiveFile.new path
-  return
+    file.check
-rescue e
+    file.close
-  e
+    return
+  rescue e
+    file.close unless file.nil?
+    e
+  end
 end
 
 def random_str