Clean/Rebuild Needed

[piboistudios]

Building does not appear to clean out the build directory before trying to write new files, causing an unhandled promise rejection:

Exporting asset 1 of 2 (Ubuntu-B.ttf).
(node:12448) UnhandledPromiseRejectionWarning: Error: EISDIR: illegal operation on a directory, readlink 'build\html5\assets\Ubuntu-B.ttf'
    at Object.readlinkSync (fs.js:836:3)
    at checkDest (C:\Users\gabri\AppData\Roaming\npm\node_modules\gecko2d\Kha\Tools\khamake\node_modules\fs-extra\lib\copy-sync\copy-sync.js:184:23)
    at checkPaths (C:\Users\gabri\AppData\Roaming\npm\node_modules\gecko2d\Kha\Tools\khamake\node_modules\fs-extra\lib\copy-sync\copy-sync.js:208:24)
    at Object.copySync (C:\Users\gabri\AppData\Roaming\npm\node_modules\gecko2d\Kha\Tools\khamake\node_modules\fs-extra\lib\copy-sync\copy-sync.js:26:24)
    at Html5Exporter.copyBlob (C:\Users\gabri\AppData\Roaming\npm\node_modules\gecko2d\Kha\Tools\khamake\out\Exporters\Html5Exporter.js:186:12)
    at Html5Exporter.copyFont (C:\Users\gabri\AppData\Roaming\npm\node_modules\gecko2d\Kha\Tools\khamake\out\Exporters\KhaExporter.js:62:27)
    at FSWatcher.watcher.on (C:\Users\gabri\AppData\Roaming\npm\node_modules\gecko2d\Kha\Tools\khamake\out\AssetConverter.js:139:61)
    at FSWatcher.emit (events.js:182:13)
    at process._tickCallback (internal/process/next_tick.js:61:11)
(node:12448) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 2)
(node:12448) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.