Dear all, I would appreciate your help on learning how to fix the following error ; thank you !

"Error: subscript is a NSBS object that is incompatible with the current subsetting operation"

I am working with 2 Granges, let's call them "query" and "subject" (as shown below), and the purpose of the R code is to "transfer" the meta-information from "mcols" of "subject" to the "query"'s GRanges that are overlapping the "subject".

> query
GRanges object with 990 ranges and 0 metadata columns:
                           seqnames                 ranges strand
                              <Rle>              <IRanges>  <Rle>
         chr1:10001-140000     chr1      [ 10001,  140000]      *
        chr1:140002-180000     chr1      [140002,  180000]      *
        chr1:340002-530000     chr1      [340002,  530000]      *
        chr1:580002-770000     chr1      [580002,  770000]      *
       chr1:900002-1800000     chr1      [900002, 1800000]      *
                       ...      ...                    ...    ...
  chrX:154150002-154260000     chrX [154150002, 154260000]      *
  chrX:154260002-154560000     chrX [154260002, 154560000]      *
  chrX:154560002-154650000     chrX [154560002, 154650000]      *
  chrX:155340002-155380000     chrX [155340002, 155380000]      *
  chrX:155460002-155500000     chrX [155460002, 155500000]      *

and

> subject
GRanges object with 1081 ranges and 1 metadata column:
                           seqnames                 ranges strand |        name
                              <Rle>              <IRanges>  <Rle> | <character>
             chr1:2-140000     chr1      [     2,  140000]      * |         CN4
        chr1:140002-180000     chr1      [140002,  180000]      * |       CN128
        chr1:340002-530000     chr1      [340002,  530000]      * |        CN32
        chr1:580002-770000     chr1      [580002,  770000]      * |         CN6
       chr1:900002-1800000     chr1      [900002, 1800000]      * |         CN3
                       ...      ...                    ...    ... .         ...
  chrX:154150002-154260000     chrX [154150002, 154260000]      * |        CN32
  chrX:154260002-154560000     chrX [154260002, 154560000]      * |         CN3
  chrX:154560002-154650000     chrX [154560002, 154650000]      * |         CN7
  chrX:155340002-155380000     chrX [155340002, 155380000]      * |       CN128
  chrX:155460002-155500000     chrX [155460002, 155500000]      * |        CN64

The R code is :

ranges <- subsetByOverlaps(query, subject)
hits <- GenomicRanges::findOverlaps(query, subject, ignore.strand=TRUE)
idx <- unique(subjectHits(hits))
values <- DataFrame(cnv_id=names(subject)[idx], cnv_type=subject$name[idx])
mcols(ranges) <- c(mcols(ranges), values)

When we type "ranges", it says :

> ranges
GRanges object with 990 ranges and 4 metadata columns:
Error: subscript is a NSBS object that is incompatible with the current
  subsetting operation

As  for the sessioninfo(), it is :

> sessionInfo()
R version 3.3.3 (2017-03-06)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Ubuntu 14.04.5 LTS

locale:
 [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C              
 [3] LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8    
 [5] LC_MONETARY=en_US.UTF-8    LC_MESSAGES=en_US.UTF-8   
 [7] LC_PAPER=en_US.UTF-8       LC_NAME=C                 
 [9] LC_ADDRESS=C               LC_TELEPHONE=C            
[11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C       

attached base packages:
[1] parallel  stats4    stats     graphics  grDevices utils     datasets
[8] methods   base     

other attached packages:
 [1] dplyr_0.7.1                tidyr_0.6.3               
 [3] plyr_1.8.4                 ggthemes_3.4.0            
 [5] ggplot2_2.2.1              reshape2_1.4.2            
 [7] HelloRanges_1.0.1          GenomicAlignments_1.10.1  
 [9] VariantAnnotation_1.20.3   Rsamtools_1.26.2          
[11] SummarizedExperiment_1.4.0 GenomicFeatures_1.26.4    
[13] AnnotationDbi_1.36.2       Biobase_2.34.0            
[15] BSgenome_1.42.0            Biostrings_2.42.1         
[17] XVector_0.14.1             rtracklayer_1.34.2        
[19] GenomicRanges_1.26.4       GenomeInfoDb_1.10.3       
[21] IRanges_2.8.2              S4Vectors_0.12.2          
[23] BiocGenerics_0.20.0       

loaded via a namespace (and not attached):
 [1] Rcpp_0.12.11       bindr_0.1          bitops_1.0-6       tools_3.3.3       
 [5] zlibbioc_1.20.0    biomaRt_2.30.0     digest_0.6.12      bit_1.1-12        
 [9] docopt_0.4.5       gtable_0.2.0       RSQLite_2.0        memoise_1.1.0     
[13] tibble_1.3.3       lattice_0.20-35    pkgconfig_2.0.1    rlang_0.1.1       
[17] Matrix_1.2-10      DBI_0.7            bindrcpp_0.2       stringr_1.2.0     
[21] bit64_0.9-7        grid_3.3.3         glue_1.1.1         R6_2.2.2          
[25] XML_3.98-1.8       BiocParallel_1.8.2 blob_1.1.0         magrittr_1.5.0    
[29] scales_0.4.1       assertthat_0.2.0   colorspace_1.3-2   stringi_1.1.5     
[33] lazyeval_0.2.0     munsell_0.4.3      RCurl_1.95-4.8