A meteorological station records daily rainfall measurements in millimeters over a period of time, stored in an array rainfall.

A programmer writes the following pseudocode to find the maximum increase in rainfall between any two consecutive days.

1 PROCEDURE maxRainfallIncrease()
2 BEGIN PROCEDURE
3     SET max_increase TO 0.0
4     FOR k FROM 0 TO LENGTH(rainfall) - 1 DO
5         SET increase TO rainfall[k + 1] - rainfall[k]
6         IF increase > max_increase THEN
7             SET max_increase TO increase
8         END IF
9     END FOR
10    RETURN max_increase
11 END PROCEDURE

The algorithm compiles successfully, but crashes due to an error on line 5 when it runs.