Wrong type (expecting real number): #<undefined> in lily-library.scm

[Ernie Braganza]

I just downloaded the unofficial 2.20.0 build for Mac (I'm using OS 10.15 "Catalina"). And I am unable to process the simplest file because I get an error from the lily-library.scm Scheme file: Wrong type (expecting real number): #<undefined>.

I've searched for this error online and I am unable to find any helpful information. Does anyone have an idea how I should proceed?

Here's my script and the error message.

\version "2.20.0"
{
  c' e' g' e'
}

Starting lilypond 2.20.0 [Test.ly]...

Processing `/Users/erniebraganza/Music/lilypond_scores/Jazz/Testing Folder/Test.ly'

Parsing...

Interpreting music...

Preprocessing graphical objects.../Applications/LilyPond.app/Contents/Resources/share/lilypond/2.20.0/scm/lily-library.scm:243:5: In procedure ly:ledger-line-spanner::set-spacing-rods in _expression_ (process-procedure book paper ...):

/Applications/LilyPond.app/Contents/Resources/share/lilypond/2.20.0/scm/lily-library.scm:243:5: Wrong type (expecting real number): #<undefined>

Exited with return code 1.

The highlighted code in lily-library.scm is:

(define (print-book-with book process-procedure)
  (let* ((paper (ly:parser-lookup '$defaultpaper))
         (layout (ly:parser-lookup '$defaultlayout))
         (outfile-name (get-outfile-name book)))
    (process-procedure book paper layout outfile-name)))