programming errors: "Object is not a markup." and "I am not spanned!"

[Marnix Klooster]

L.S.,

For the following file

    \version "2.12.4"
    { R\breve\fermata }

lilypond reports the following "programming error":

    $ lilypond bug.ly
    GNU LilyPond 2.12.4
    Processing `bug.ly'
    Parsing...
    Interpreting music...
    Preprocessing graphical objects...
    programming error: Object is not a markup.
    continuing, cross fingers
    This object should be a markup: ()
    Finding the ideal number of pages...
    Fitting music on 1 page...
    Drawing systems...
    programming error: cannot align on self: empty element
    continuing, cross fingers
    Layout output to `bug.ps'...
    Converting to `./bug.pdf'...
    $ 

Even more alarming-looking,

    \version "2.12.4"
    { R2 }

results in a (correct) "barcheck failed" warning, but also in an "I am not 
spanned!" error:

    $ lilypond bug2.ly
    GNU LilyPond 2.12.4
    Processing `bug2.ly'
    Parsing...
    Interpreting music...
    bug2.ly:2:2: warning: barcheck failed at: 1/2
    {
      R2 }
    Preprocessing graphical objects...
    programming error: Multi_measure_rest::get_rods (): I am not spanned!
    continuing, cross fingers
    programming error: Object is not a markup.
    continuing, cross fingers
    This object should be a markup: ()
    programming error: Multi_measure_rest::get_rods (): I am not spanned!
    continuing, cross fingers
    Finding the ideal number of pages...
    Fitting music on 1 page...
    Drawing systems...
    Layout output to `bug2.ps'...
    Converting to `./bug2.pdf'...
    $

(Probably irrelevant, but I'm running under cygwin.)

Groetjes,
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Marnix