fix off by one error for completion-replace option (#10279)

helix-lsp/src/lib.rs

@@ -284,7 +284,8 @@ pub mod util {
                 .chars_at(cursor)
                 .skip(1)
                 .take_while(|ch| chars::char_is_word(*ch))
-                .count();
+                .count()
+                + 1;
         }
         (start, end)
     }