Installation problems. Grunt (serve).

[TravelTrader]

I cloned it and npm install leads to

npm WARN optional Skipping failed optional dependency /chokidar/fsevents:
npm WARN notsup Not compatible with your operating system or architecture: [email protected]
npm WARN optional Skipping failed optional dependency /karma/chokidar/fsevents:
npm WARN notsup Not compatible with your operating system or architecture: [email protected]
npm WARN [email protected] requires a peer of grunt@~0.4.1 but none was installed.

But grunt --version:

grunt-cli v1.2.0
grunt v1.0.4

After npm start this is the content of the debug file:

0 info it worked if it ends with ok
1 verbose cli [ '/usr/bin/node', '/usr/bin/npm', 'start' ]
2 info using [email protected]
3 info using [email protected]
4 verbose run-script [ 'prestart', 'start', 'poststart' ]
5 info lifecycle [email protected]~prestart: [email protected]
6 silly lifecycle [email protected]~prestart: no script for prestart, continuing
7 info lifecycle [email protected]~start: [email protected]
8 verbose lifecycle [email protected]~start: unsafe-perm in lifecycle true
9 verbose lifecycle [email protected]~start: PATH: /usr/share/npm/bin/node-gyp-bin:/var/www/html/techan.js/node_modules/.bin:/home/gandhi/.local/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin
10 verbose lifecycle [email protected]~start: CWD: /var/www/html/techan.js
11 silly lifecycle [email protected]~start: Args: [ '-c', 'grunt serve' ]
12 silly lifecycle [email protected]~start: Returned: code: 3  signal: null
13 info lifecycle [email protected]~start: Failed to exec start script
14 verbose stack Error: [email protected] start: `grunt serve`
14 verbose stack Exit status 3
14 verbose stack     at EventEmitter.<anonymous> (/usr/share/npm/lib/utils/lifecycle.js:232:16)
14 verbose stack     at emitTwo (events.js:126:13)
14 verbose stack     at EventEmitter.emit (events.js:214:7)
14 verbose stack     at ChildProcess.<anonymous> (/usr/share/npm/lib/utils/spawn.js:24:14)
14 verbose stack     at emitTwo (events.js:126:13)
14 verbose stack     at ChildProcess.emit (events.js:214:7)
14 verbose stack     at maybeClose (internal/child_process.js:925:16)
14 verbose stack     at Process.ChildProcess._handle.onexit (internal/child_process.js:209:5)
15 verbose pkgid [email protected]
16 verbose cwd /var/www/html/techan.js
17 error Linux 4.15.0-50-generic
18 error argv "/usr/bin/node" "/usr/bin/npm" "start"
19 error node v8.10.0
20 error npm  v3.5.2
21 error code ELIFECYCLE
22 error [email protected] start: `grunt serve`
22 error Exit status 3
23 error Failed at the [email protected] start script 'grunt serve'.
23 error Make sure you have the latest version of node.js and npm installed.
23 error If you do, this is most likely a problem with the techan package,
23 error not with npm itself.
23 error Tell the author that this fails on your system:
23 error     grunt serve
23 error You can get information on how to open an issue for this project with:
23 error     npm bugs techan
23 error Or if that isn't available, you can get their info via:
23 error     npm owner ls techan
23 error There is likely additional logging output above.
24 verbose exit [ 1, true ]

I think it's similar to #64 (I am located in Europe/Germany) but I don't want to learn about docker. Or isn't it possible with npm for me?
I would be happy if you could help me get this fabulous tool running.
Thank you!