[developers] Tree export error message

[Micha Jellinghaus]

Hi Stephan,

> it seems GG redefines an [incr tsdb()] function in `lkb/user-fns.lsp'.
> i must deny all responsibility under these circumstances.  but if you
> commented out the offending version of export-tree(), probably you are
> back to a working configuration :-).
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Thanks a lot! Commenting out the redefined version solved the problem
(provided I didn't lose anything else without noticing it).

Best,
Micha.