SVG output with 2.19.31

[Andrew Bernard]

Is anybody using SVG with 2.19.31?

I am seeing this error:

Layout output to `sonata-page-1.svg'...

warning: cannot find SVG font #f

warning: cannot find SVG font #f

/home/andro/lilypond/usr/share/lilypond/current/scm/output-svg.scm:428:30: In procedure string-join in _expression_ (string-join (map # glyphs) "

"):

/home/andro/lilypond/usr/share/lilypond/current/scm/output-svg.scm:428:30: Wrong type (expecting string): #<unspecified>

This is just a heads up to see if this is a known issue. My score is extremely long and complex, and I am attempting to binary chop it to narrow down the issue now, but I thought I would probe the list first.

I am using fonts such as lilyboulez, but commenting the custom fonts out make no difference to the error. I am seeing this error on Ubuntu 15.04 and openSUSE Leap 42.1.

Andrew