/bin/board_detect: /etc/board.d/02_network: line 190: divide by zero

As in the title, the following error appears during booting:
/bin/board_detect: /etc/board.d/02_network: line 190: divide by zero
The problem, however, is that /bin/board_detect doesn't have a 190 lines, and the 190 line in /etc/board.d/02_network doesn't seem to be a problem, as it's left as it was in the original.
My guess is that something is dynamically changed during execution, hence the 190 line mentioned.
Of the changes to the /etc/board.d/02_network file, I added the following:

	generic,mt02_m300-mt9533)
		ucidef_add_switch "switch0" \
			"0@eth0"
		;;
	generic,mt02_m300-mt9341)
		ucidef_add_switch "switch0" \
			"2:lan"
		;;

These devices have only one Ethernet port, in the first case it is connected to port 0, and in the second to port 2.
How can this problem be fixed?