Failed to find project files. No such file or directory: '/home/<username>/project'

Hi! I’m very new to Snapcraft, stumbling my way through online tutorials and example .yaml files trying to package my application with Snapcraft.
I suspect there will be many more errors along the way, but the first one is:

Failed to find project files.
Traceback (most recent call last):
  File "/snap/snapcraft/3440/lib/python3.5/site-packages/snapcraft/cli/", line 117, in get_project
    os.chdir(os.path.expanduser(os.path.join("~", "project")))
FileNotFoundError: [Errno 2] No such file or directory: '/home/user/project'

Here’s my complete snapcraft.yaml:

name: giraffe-commander
summary: File Commander
version: "0.9"
description: |
  Native Linux dual-panel file manager (akin to Krusader or Total Commander)
icon: qt-app/resources/icon.png

base: core18
confinement: strict
    plugin: qmake
    options: "-r"
    project-files: ""
    source: .

    command: bin/FileCommander
    - bin/desktop-launch
      "DISABLE_WAYLAND": "1"

I don’t think the “project-files” option should be set as qmake is capable of finding the project file just fine; the problem is something else. Any advice, please?
I’m calling snapcraft from the project’s root directory, which is of course not the home directory itself.

P. S. Is it possible to build a Snapcraft package from an already built executable and libraries (omitting building from source), and package Qt libraries from a specified location?