Fix len(t) == L` the length of the table changed while iterating over it when cleaning zombie entries in pileup

[andreas-wilm]

$ ~/genomics/lofreq3.git/lofreq call -r chr17:45623485-55623409 -b Sample2.sorted.remdup.bqsr.rg.bam -f ~/genomics/data/hg19.fa /home/wilma/.nimble/pkgs/cligen-0.9.41/cligen.nim(920) lofreq /home/wilma/.nimble/pkgs/cligen-0.9.41/cligen.nim(584) multiSubs /home/wilma/.nimble/pkgs/cligen-0.9.41/cligen.nim(664) multi /home/wilma/.nimble/pkgs/cligen-0.9.41/cligen.nim(584) dispatchcall /home/wilma/genomics/lofreq3.git/src/lofreqpkg/pileup/pileup.nim(109) call /home/wilma/genomics/lofreq3.git/src/lofreqpkg/pileup/pileup.nim(63) fullPileup /home/wilma/genomics/lofreq3.git/src/lofreqpkg/pileup/algorithm.nim(155) pileup /home/wilma/genomics/lofreq3.git/src/lofreqpkg/pileup/processor.nim(234) done /home/wilma/genomics/lofreq3.git/src/lofreqpkg/pileup/storage/slidingDeque.nim(179) flushAll /home/wilma/genomics/lofreq3.git/src/lofreqpkg/pileup/storage/slidingDeque.nim(106) resetDeq /home/wilma/genomics/lofreq3.git/src/lofreqpkg/pileup/storage/slidingDeque.nim(101) submitDeq /home/wilma/genomics/lofreq3.git/src/lofreqpkg/pileup/postprocessing.nim(34) callAndPrint /home/wilma/genomics/lofreq3.git/src/lofreqpkg/call.nim(228) callAtPos /home/wilma/genomics/lofreq3.git/src/lofreqpkg/pileup/storage/containers/operationData.nim(37) clean /home/wilma/.choosenim/toolchains/nim-1.2.0/lib/pure/collections/tables.nim(707) clean /home/wilma/.choosenim/toolchains/nim-1.2.0/lib/system/assertions.nim(29) failedAssertImpl /home/wilma/.choosenim/toolchains/nim-1.2.0/lib/system/assertions.nim(22) raiseAssert /home/wilma/.choosenim/toolchains/nim-1.2.0/lib/system/fatal.nim(49) sysFatal Error: unhandled exception: /home/wilma/.choosenim/toolchains/nim-1.2.0/lib/pure/collections/tables.nim(707, 13) len(t) == L the length of the table changed while iterating over it [AssertionError] (

[andreas-wilm]

Happens while cleaning zombie entries ("n":{"-1":1}) by iterating over keys() and changing the table