exception: __concat not defined for operands: null and

[GoogleCodeExporter]

What cartridge are you playing?
Unreleased beta cartridge attached.

What is your phone/PDA manufacturer and model? What GPS are you using?
Asus Nexus 7 (2013) Android 4.4.2

What steps will reproduce the problem?
1. Start cartridge
2. Click "Start"
3. Click "OK"
4. Navigate to "Village"
5. Once inside, exception appears

What is the expected output? What happens instead?
It should show me the debugging information that I've programmed into the 
cartridge.

If you see an error screen, please type its contents here:
(See also attached picture file.)
You hit a bug! please report at openwig.google.com and i'll fix it for you!
java.lang.RuntimeException: __concat not defined for operands: null and

stack trace: at @E:/webtempfiles/9c9460f3-aafa-4b4f-979b-5e4f25c4e16a/
FoxGooseandGrain.enc:1154
at @E:/webtempfiles/9c9460f3-aafa-4b4f-979b-5e4f25c4e16a/
FoxGooseandGrain.enc:909

What version are you using?
WhereYouGo 0.6.0

Please provide any additional information below.
There is an actual bug in my code (causing the null), but the exception 
requests a
bug report.

Original issue reported on code.google.com by Val...@gmail.com on 26 Dec 2013 at 5:43

Attachments:

• Screenshot_2013-12-25-22-24-56.png
• FoxGooseandGrain.gwc

[GoogleCodeExporter]

This was compiled as a Play Anywhere cartridge though the final one will not be.

Original comment by Val...@gmail.com on 26 Dec 2013 at 5:44

[GoogleCodeExporter]

well, it appears that you are inserting null value into a string somewhere.
could be that you are trying to display a variable that is not set.

what is on line 1154 of your generated Lua file?

Original comment by matej...@gmail.com on 26 Dec 2013 at 10:00

[GoogleCodeExporter]

Yes, there is a problem with concatenating nulls.  I said this in my initial 
bug report.  If this is not the type of error that should be reported then this 
issue should be closed.  If this is just a generic error message about 
reporting exceptions, it should point to a list (on your page) of types of 
exceptions (like concatenating nulls) that should not be entered as nulls.  I 
also reported in my initial bug report that I'm only reporting it because a bug 
report is requested in the exception message.

However, the error message is also incomplete in the part "__concat not defined 
for operands: null and".  The problem is the "and".  Is it just complaining 
about the null itself, in which case there should be no "and"; or is it saying 
that the null is being concatenated with something that "I'm not going to tell 
you about"?

Again, I initially reported it because the message with the exception requested 
a bug report.  If this is a known problem that should not be fixed, then just 
close it.

Original comment by Val...@gmail.com on 26 Dec 2013 at 4:47

[GoogleCodeExporter]

ah, sorry, i didn't finish reading the report.  my bad.

the message requests a bug report, because this exception can in some cases 
originate from the openwig core (e.g., if you concatenated a value that is not 
supposed to be null, but it is null due to openwig bug). I missed the part 
where you say that this is caused by a bug in your code, so i was asking 
whether it could be a bug in your code ;e)

having a wiki page with common exceptions and what triggers them is a good idea.

i believe that "null and" part means that the other part is empty string - IOW, 
it should be " null and '' ". could that be the case?
i'll keep this bugreport open to investigate whether this should be fixed.

Original comment by matej...@gmail.com on 26 Dec 2013 at 6:08

[GoogleCodeExporter]

Embarrassingly, I sometimes (still too often) don't read all of some text 
either, so I certainly understand; it is no problem now that we understand each 
other.

It could very well mean "null and empty string" because I was still debugging 
it.  I've changed how I'm debugging it now though.  Nevertheless, you should (I 
hope) still be able to debug it from the cartridge I uploaded.  Thanks for 
considering my bug report.

Original comment by Val...@gmail.com on 26 Dec 2013 at 6:27