Fix END-IF error being thrown for END-FOR

[davidjb]

If a template an errant END-FOR command, the current behaviour is to throw an error with the text:

Unexpected END-IF outside of IF statement context: end-for person

However, the command message is describes the wrong command/structure used.

This PR changes the outputted error message to report the command name used and corresponding context, working for both END-IF/END-FOR commands.

This can be reproduced with a template like this, with just the following text and nothing else:

+++END-FOR person+++

[jjhbw]

Great find, this does indeed look like a mistake! I'll test, merge, and release this on Monday.