regions must be an array (or undefined): a Set passed the per-id check, then was dropped because it has no length, and a string was read character by character ("10" as the ids "1" and "0"). The ids themselves are checked by regionProblem.
regions
undefined
Set
length
"10"
regionProblem
regionsmust be an array (orundefined): aSetpassed the per-id check, then was dropped because it has nolength, and a string was read character by character ("10"as the ids "1" and "0"). The ids themselves are checked byregionProblem.