Remove duplicates from TK list to avoid crashes

Otherwise it throws an error because, while rendering the TK tags,
you're not allowed to have one TK come more than once. That aside,
we don't want *each* occurrence having its own table column, do we?

src/App.svelte

@@ -32,6 +32,9 @@
 			}
 		}
 
+		// remove duplicates
+		tkList = [...new Set(tkList)]
+
 		return tkList
 	}