I think this is correct, your query statement is 'SELECT pgr_alphaShape((st_collect(v.the_geom))) as geom FROM ways_vertices_pgr as v, result as r WHERE r.node = v.id;'. The return value of the pgr_alphaShape function is a GEOMETRY COLLECTION.
For reference, please seehttps:// docs.pgrouting.org/3.6/en/pgr_alphaShape.html. Sorry, I went through a long vacation.
