Recently I bumped into an issue where a query, ran using the DBI library with the dbGetQuery function returned an integer64. Even without me noticing it. When converting my data frame (or data.table) to a matrix for clustering purposes, I ran into the following error:
Error in if (changes == 0) break : missing value where TRUE/FALSE needed
After inspection of the table, I found that the data.matrix() function was unable to automatically convert integer64 values.
You can solve this issue retroactively by converting the integer64 into a double, as follows (data.table syntax):
dt[,COLUMN_NAME := as.double(COLUMN_NAME)]
However, you can solve the issue proactively by setting a specific parameter when connecting to the database.
dbConnect(db, bigint = 'integer', ...)
You can find more about it in the DBI documentation:

Great success!