segfault during copy into foreign table

I made a core dump; the backtrace is:

#0 0x0000555d6dd6d128 in CheckExprStillValid ()
#1 0x0000555d6dd6d230 in ExecInterpExprStillValid ()
#2 0x0000555d6dd0a54d in NextCopyFrom ()
#3 0x00007fa636521871 in CopyIntoCStoreTable (queryString=, copyStatement=) at cstore_fdw.c:594
#4 CStoreProcessCopyCommand (completionTag=0x7ffd48351980 "", queryString=, copyStatement=) at cstore_fdw.c:493
#5 CStoreProcessUtility (plannedStatement=, queryString=, context=, paramListInfo=,
queryEnvironment=0x0, destReceiver=0x555d7016b9c0, completionTag=0x7ffd48351980 "") at cstore_fdw.c:293
#6 0x0000555d6ded0d14 in ?? ()
#7 0x0000555d6ded17c7 in ?? ()
#8 0x0000555d6ded242e in PortalRun ()
#9 0x0000555d6dece337 in ?? ()
#10 0x0000555d6decfdf0 in PostgresMain ()
#11 0x0000555d6de5ac6a in ?? ()
#12 0x0000555d6de5bb91 in PostmasterMain ()
#13 0x0000555d6dbe4258 in main ()