Blocks #3051251: Existing menu links show validation issues on migration (and ALL menu links pointing to node translations are invalid) if it will solved by menu link migration derivatives.
Problem/Motivation
For being able to properly migrate menu links (without depending on every content entities' migration), we should be able to create stub menu links.
Right now, this is blocked by the Route migrateprocess plugin, because it assumes that the $options variable it populates form the input value array is an array.
Proposed resolution
Before merging with $route['options], check whether the local $options variable is an array or not.