sphinx doc not installed when creating a new application

[fraya]

deft: v0.13.0 built on 2025-06-21T22:26:52+00:00

I have not installed Sphinx docs:

$ deft new application hello-world
Downloaded pacman-catalog@master to /home/fraya/Dylan/_packages/pacman-catalog/master/src/
Created library hello-world-app.
Created library hello-world.
Created library hello-world-test-suite.
Downloaded strings@1.1.0 to /tmp/hello-world/_packages/strings/1.1.0/src/
Downloaded command-line-parser@3.1.1 to /tmp/hello-world/_packages/command-line-parser/3.1.1/src/
Downloaded json@1.0.0 to /tmp/hello-world/_packages/json/1.0.0/src/
Downloaded testworks@3.3.0 to /tmp/hello-world/_packages/testworks/3.3.0/src/
Downloaded sphinx-extensions@1.1.0 to /tmp/hello-world/_packages/sphinx-extensions/1.1.0/src/
Updated 18 of 18 registry files in /tmp/hello-world/registry/.
WARNING: Unable to generate documentation boilerplate due to an error when running the sphinx-quickstart command.
Command: sphinx-quickstart --sep --project hello-world --author fraya -v 0.1.0 --extensions dylan.domain --quiet /tmp/hello-world/doc/
Exit status: 127
Output: sh: 1: sphinx-quickstart: not found

While this isn't incorrect, I think the error message could perhaps be improved by checking for the program's existence before running it, avoiding the lines

Command: sphinx-quickstart --sep --project hello-world --author fraya -v 0.1.0 --extensions dylan.domain --quiet /tmp/hello-world/doc/
Exit status: 127
Output: sh: 1: sphinx-quickstart: not found

that can be shown when there is an error running the sphinx-quickstart command.

Perhaps creating the documentation should be optional, either because users may want simple Markdown documents in GH or may not want to install the Sphinx dependency.