It would be useful if a missing property in the config file fell back gracefully to the default value, rather than killing the process with a hard error.

Is there any appetite for such a change? We could potentially specify default values in a json file that the C++ code reads at compile time and the python script valhalla_build_config parses at runtime?

TilePix only supports orthogonal maps (currently - hopefully we'll be able to support other types in the future). A sensible error should be returned on Reading a map which doesn't have orientation="orthogonal".

Need to set up a constant for each type:

• orthogonal
• hexagonal
• isometric
• staggered

Then, using a switch statement, check against each, returning an error if not