your package includes some files that seem to lack sources
in preferred forms of modification:
File test/compare/esprima.js includes two line generated from:
tools/generate-unicode-regex.py that is missing.
This line should be injected at build time
According to Debian Free Software Guidelines  (DFSG) #2:
"The program must include source code, and must allow distribution
in source code as well as compiled form."
In some cases this could also constitute a license violation for some
copyleft licenses such as the GNU GPL. (While sometimes the licence
allows not to ship the source, the DFSG always mandates source code.)
In order to solve this problem, you could:
1. add the source files to "debian/missing-sources" directory.
2. repack the origin tarball and add the missing source files to it.
Both way satisfy the requirement to ship all source code. The second option
might be preferable due to the following reasons :
- Upstream can do it too and you could even supply a patch to them, thus
full filling our social contract , see particularly §2.
- If source and non-source are in different locations, ftpmasters may
miss the source and (needlessly) reject the package.
- The source isn't duplicated in every .diff.gz/.debian.tar.* (though
this only really matters for larger sources).
You could also ask debian...@lists.debian.org or #debian-qa for more