ClangUpdateQuickFix() crashes constantly

[twesterhout]

• I open a file in nvim
• do :messages
• do :call ClangUpdateQuickFix()

This results in the following error output:

"include/boost/static_views/concepts.hpp" 251L, 6757C
Error detected while processing function ClangUpdateQuickFix[1]..<SNR>32_DoPeriodicQuickFix[8]..<SNR>32_ClangQuickFix[5]..provider#python#Call:
line   18:                  
ch 2 was closed by the client
Error detected while processing function ClangUpdateQuickFix[1]..<SNR>32_DoPeriodicQuickFix[8]..<SNR>32_ClangQuickFix[6]..provider#python#Call:
line   18:                  
Invalid channel: 2
Error detected while processing function ClangUpdateQuickFix[1]..<SNR>32_DoPeriodicQuickFix[8]..<SNR>32_ClangQuickFix:
line   23:
E121: Undefined variable: l:list
E116: Invalid arguments for function setqflist

Some info:

• NVIM v0.2.1-814-g0f2873c
• python 3.4.2
• clang 6.0.0