RuntimeException with many PDFs

First, thanks for this great library 👍 .

I am getting a `Parse error occurred : Unexpected RuntimeException from org.apache.tika.parser.pdf.PDFParser` with many PDFs. I tested some of those PDFs directly with Tika and they work fine there.

Here is one example to reproduce the error: https://pmc.ncbi.nlm.nih.gov/articles/PMC3183543/pdf/jls373.pdf

