The app stops if map_files[].src is invalid without error

[daisukes]

NavCog tries to parse the src string as an URL.
If it is not a valid URL, it will stop while checking download files.

{
   ...
    "map_files":
    [
      {
        "src": "invalid_url:port/path/to/file",
        "size": 1234567
      }
    ],
   ...
}

This returns nil

NavCogIOSv3/NavCog3/ServerConfig.m

Lines 410 to 412 in 5d281f6

	- (NSURL*) getDestLocation:(NSString*)path {
	return [NSURL URLWithString:[NSURL URLWithString:path].lastPathComponent relativeToURL:targetDir];
	}

and here causes an exception.

NavCogIOSv3/NavCog3/ServerConfig.m

Line 379 in 5d281f6

[maps addObject:[self getDestLocation:src].path];