Why does `scripts/examples/DataTypes.thy` report failure in the wrong line

[phlegmaticprogrammer]

Running the script gives the message

failed executing theory \examples\DataTypes at row 56, column 17:
  values cannot be compared: ["a", "c"], ["b"]

In that message, it should be row 55, not row 56.

[phlegmaticprogrammer]

Cannot really replicate this problem anymore after fixing a couple of others. Will close it for now.