GUILE error reporting has changed for worse in 2.15 (compared to 2.12), useless now

[Reinhold Kainhofer]

An example is attached. It contains just a faulty music-function that crashes 
guile (car and cdr expect a pair, not an empty list):

aa = #(define-music-function (a b) () (car '()))
{ a\aa }


In 2.12, when you had an error in some GUILE code, lilypond would print out 
the error together with the location where the error occured

GNU LilyPond 2.12.3
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crash.ly:4:2: In procedure car in expression (car (quote ())):
crash.ly:4:2: Wrong type (expecting pair): ()


However, in lilypond 2.15.9 (and probably also some earlier versions), 
lilypond suddenly only prints out the error message, but not where the error 
occurred (neither file nor expression is displayed):

GNU LilyPond 2.15.9
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ERROR: Wrong type (expecting pair): ()


As you can imagine, from this error output it is basically impossible to find 
the correct location of broken guile code somewhere in out scm/ directory (see 
also my comment at issue 1.770, which I wouldn't have been able to fix without 
the 2.12 error message)


Is there any way to revert GUILE's error reporting back to the 2.12 "verbose" 
output? 
I think this deserves a bug report with priority "High", according to the 
latest GOP-8 ("anything which makes it difficult for serious contributors to 
help out (e.g. difficult to find the relevant source tree(s), [...]).")

Cheers,
Reinhold

-- 
------------------------------------------------------------------
Reinhold Kainhofer, address@hidden, http://reinhold.kainhofer.com/
 * Financial & Actuarial Math., Vienna Univ. of Technology, Austria
 * http://www.fam.tuwien.ac.at/, DVR: 0005886
 * LilyPond, Music typesetting, http://www.lilypond.org

crash.ly
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