Location constructor
Creates a new Location instance.
Validates that coordinates are within valid ranges.
Throws ArgumentError if coordinates are outside valid ranges.
Implementation
Location({required this.lat, required this.lng})
: assert(lat >= -90.0 && lat <= 90.0,
'Latitude must be between -90.0 and 90.0'),
assert(lng >= -180.0 && lng <= 180.0,
'Longitude must be between -180.0 and 180.0');