invalid character indexing

Warning: Found the following features in more than one assay, excluding the default. We will not include these in the final data frame: Lyz2, Col3a1, Col1a1, Col1a2, Rpl39l, Gm11361, Eif4a2, S100a8, S100a9, Nkg7, Ccl5, Gzmk, Top2a, Mki67, Tuba1b, Pecam1, Cdh5, Eng
Warning: Could not find Cd68 in the default search locations, found in RNA assay instead
Error in intI(j, n = d[2], dn[[2]], give.dn = FALSE) : 
  invalid character indexing
In addition: Warning message:
In cells.idents["NA"] <- names(x = which(x = is.na(x = Idents(object = object)[cells]))) :
  number of items to replace is not a multiple of replacement length

Error in intI(j, n = d[2], dn[[2]], give.dn = FALSE) : invalid character indexing