Check if tempPath Exists Before Unlinking

[ghost]

Do we need to move L18 into the if conditional?

For example:

if (fs.existsSync(tempPath)) {
    delete this._downloads[tileKey];
    fs.unlinkSync(tempPath);
}

[ghost]

References: #16

[ghost]

Upon further inspection, it would appear this is an issue with L6 in hgt.js:

var fd = fs.openSync(path, 'r'),

[ghost]

Could the error occur because the coords N21, E122 are in the ocean where there is probably no saved data or does the module account for this?

The errors I'm getting:

{ [Error: ENOENT: no such file or directory, open '/var/folders/bf/n6q0w74n6dvct5w16mpj2d_h0000gn/T/F51.zip']
  errno: -2,
  code: 'ENOENT',
  syscall: 'open',
  path: '/var/folders/bf/n6q0w74n6dvct5w16mpj2d_h0000gn/T/F51.zip' }

And more commonly:

{ Error: ENOENT: no such file or directory, open '/Users/alex/rw/ggr-navigation-cloud/functions/shared/util/data/N21E122.hgt'
    at Object.openSync (fs.js:436:3)
    at new Hgt (/Users/alex/rw/ggr-navigation-cloud/node_modules/node-hgt/src/hgt.js:6:17)
    at /Users/alex/rw/ggr-navigation-cloud/node_modules/node-hgt/src/load-tile.js:28:35
    at /Users/alex/rw/ggr-navigation-cloud/node_modules/node-hgt/src/imagico.js:50:9
    at tryCallOne (/Users/alex/rw/ggr-navigation-cloud/node_modules/promise/lib/core.js:37:12)
    at /Users/alex/rw/ggr-navigation-cloud/node_modules/promise/lib/core.js:123:15
    at flush (/Users/alex/rw/ggr-navigation-cloud/node_modules/asap/raw.js:50:29)
    at process._tickCallback (internal/process/next_tick.js:61:11)
  errno: -2,
  syscall: 'open',
  code: 'ENOENT',
  path:
   '/Users/alex/rw/ggr-navigation-cloud/functions/shared/util/data/N21E122.hgt' }

Code Ref:

const path = require('path')
const {SyncTileSet} = require('../functions/shared/util/ElevationUtils');

function prepareElevationData() {
  const p = path.resolve(__dirname, '../functions/shared/util/data/')
  console.log('Downloading elevation data to path:', p)
  const tileset = new SyncTileSet(p, [21, 119], [26, 123], function(err) {
    if (err) {
      console.log('There was an error retrieving the latest elevation data, please try again.')
      console.error(err)
      return
    }

    console.log('Elevation data successfully downloaded.')
  })
}

prepareElevationData()

[ghost]

Stepping through the code I've found the following:

Requesting LatLon[26, 122] returns the following URL:

http://www.imagico.de/map/dem_json.php?date=&lon=122&lat=26&lonE=122&latE=26&vf=1

Which returns the response:

[{"name":"G51.zip","title":"","link":"http:\/\/www.viewfinderpanoramas.org\/dem3\/G51.zip","date":"2012-06-08","lon_start":"120","lat_start":"24","lon_end":"126","lat_end":"28","type":"2"}]

Downloading the link from the above response, I get a zip file that does not include N26E122. It looks like the module is failing when it cannot find a file.