1. A computer-implemented method of identifying anomalous conditions in a database of map data, the method comprising: storing a set of distinct autocheck types, each autocheck type associated with a category of anomalous condition and indicating, when applied to a portion of map data, whether the associated category of anomalous condition is present within the portion, wherein the set of distinct autocheck types comprises a signs autocheck type; automatically applying a plurality of the stored autocheck types to the database of map data, wherein applying the signs autocheck type comprises: identifying, in a portion of the map data, a sign indicating a distance to a destination within the map data; identifying a plurality of paths from the sign having path lengths within some threshold distance of the indicated distance; and determining that an anomalous condition is present in the portion of the map data, responsive to none of the paths arriving at the indicated destination; and for each applied autocheck type, and for portions of the map data for which the autocheck type indicates that the associated category of anomalous condition is present, creating an issue entry within an issue database that references the autocheck type and the portion of the map data within which the associated anomalous condition is present.