Rendering error for the input \mathop{\Gamma}

[physikerwelt]

Warning:uninitialized:value Use of uninitialized value value in string eq
  at /usr/local/share/perl/5.18.2/LaTeXML/Package/TeX.pool.ltxml line 4962
  In Core::Definition::Constructor[\\mathop... from TeX.pool.ltxml line 5995

Error:malformed:ltx:XMWrap <ltx:XMWrap> isn't allowed in <ltx:document>
  at Literal String \\begin{doc; line 1 col 16
  Currently in XMLDocument[140319271972576]<ltx:document _box=\"LaTeXML::Core::Whatsit=HASH(0x...\" _font=\"Font[serif,medium,upright,10,b...\" xmlns=\"http://dlmf.nist.gov/LaTeXML\">...
  In Core::Document[@0x7f9e9fec61f8] at Literal String \\begin{doc; line 1 col 16
   <= Core::Definition::Constructor[\\mathop... <= Whatsit[\\mathop,Box[�]] <= Core::Document[@0x7f9e9fec61f8] <= ...

Warning:uninitialized:value Use of uninitialized value value in hash element
  at /usr/local/share/perl/5.18.2/LaTeXML/Common/Font.pm line 665
  In Core::Document[@0x7f9e9fec61f8] at Literal String \\begin{doc; line 1 col 16

Warning:uninitialized:value Use of uninitialized value value in hash element
  at /usr/local/share/perl/5.18.2/LaTeXML/Common/Font.pm line 665
  In Core::Document[@0x7f9e9fec61f8] at Literal String \\begin{doc; line 1 col 16

Conversion complete: 3 warnings; 1 error.

Fatal:misdefined:LaTeXML::Post::Document::setDocument_internal Can't call method 'getNamespaces' on an undefined value
  at /usr/local/share/perl/5.18.2/LaTeXML/Post.pm line 717.
  In Post::Document[] ->setDocument_internal
   <= Post::Document[] <= Post::XSLT[@0x7f9ea4aa2e20]
1 fatal error

Post-processing complete: 1 fatal error
Status:conversion:3

[brucemiller]

Both the integral and the \mathop{\Gamma} produce exactly what I'd expect, look like the pdf, and without any errors or warnings. So, not sure exactly what the issue is, without a small test case to go by.