Dune allows the creation of projects starting with numbers and the error message when building doesn't say it can't

[hughesjs]

Expected Behavior

Dune should refuse to create a project with a name that begins with a digit.
If Dune attempts to build a module whose name starts with a digit, the error message should indicate that it can't do so.

Actual Behavior

It creates the project skeleton.
The error on build reads:

Error: "01_module" is an 
invalid module name. Module names must be non-empty and composed only 
of the following characters: 'A'..'Z', 'a'..'z', '_', ''' or '0'..'9'. 
Hint: M01_calorie_counting would be a correct module name

Which, while the hint is useful, would actually imply that the name is okay as is.

Reproduction

dune init project 01_module
cd 01 module
dune build

Specifications

• Version of dune (output of dune --version): 3.9.1
• Version of ocaml (output of ocamlc --version) 5.0.0
• Operating system (distribution and version): 6.4.4-arch1-1

[Alizter]

It's very likely we currently do little to no validation in dune init. It shouldn't be a problem to do so.

[hughesjs]

So I'm not 100% sure if the same restriction actually applies to the library name too, it might just be the module name, so I don't know if we want that additional validation in dune init or whether we should just adjust the error message on build as in #8253. I'll need some feedback from people who have used OCaml for more than a day on that one...