On invalid config with wrong entities, fail harder

[nathan-gs]

Currently when an entity without lat/long is set, or other issues (not detectable in the Config classes) it fails and continues. It would be better to fail completely. On certain browsers a massive amount of logs are generated.

[nathan-gs]

Also linked to #91

[realzoulou]

@nathan-gs Would "fail harder" contradict with #91, which basically asks for "ignore as good as possible" and show at least the rest of entities where lat/long is available and the map in background?

[nathan-gs]

Currently it fails with 1000s of logs, but continues to render the map, but not the entities. It should stop processing if an entity is invalid (maybe it can continue with the rest).