Hey, not sure if you're still maintaining this lib at all, but thought I'd point out an issue I've encountered.
Here is the line at fault: SimplePDFParser.js:L3
For me, I don't have that path "node_modules/pdfjs-dist/es5/build/pdf", only "node_modules/pdfjs-dist/build/pdf".
I noticed that your current package.json calls for pdfjs-dist@^2.4.456 -- after installing simple-pdf and checking the version of pdfjs-dist that was installed, its package.json shows version 2.14.305. Perhaps they've updated their build folder structure since v2.4. Just wanted to bring this to your attention.