MethodError upon using Pkg.add() with a PackageSpec with unspecified version

[topolarity]

$ cat Project.toml
name = "FooPackage"
uuid = "7da9e4b2-06fe-11ef-02e0-95e6aca98d3b"
$ julia +nightly --project=. -e "using Pkg; Pkg.add(Pkg.PackageSpec(name=\"SuiteSparse\", uuid=\"4607b0f0-06f3-5cda-b6b1-a6196a1729e9\"))"
    Updating registry at `~/.julia/registries/JuliaComputingRegistry.toml`
    Updating registry at `~/.julia/registries/JuliaHubRegistry.toml`
    Updating registry at `~/.julia/registries/JuliaSimRegistry.toml`
    Updating registry at `~/.julia/registries/PumasRegistry.toml`
    Updating registry at `~/.julia/registries/TestRegistry.toml`
    Updating registry at `~/.julia/registries/githubjuliaregistryjdb.toml`
    Updating registry at `~/.julia/registries/gitlabjuliaregistryjdb.toml`
   Resolving package versions...
ERROR: MethodError: no method matching thispatch(::Nothing)
The function `thispatch` exists, but no method is defined for this combination of argument types.

Closest candidates are:
  thispatch(::VersionNumber)
   @ Base version.jl:233

Stacktrace:
 [1] add(ctx::Pkg.Types.Context, pkgs::Vector{Pkg.Types.PackageSpec}, new_git::Set{Base.UUID}; preserve::Pkg.Types.PreserveLevel, platform::Base.BinaryPlatforms.Platform, target::Symbol)
   @ Pkg.Operations ~/.julia/juliaup/julia-nightly/share/julia/stdlib/v1.12/Pkg/src/Operations.jl:1523
 [2] add
   @ ~/.julia/juliaup/julia-nightly/share/julia/stdlib/v1.12/Pkg/src/Operations.jl:1481 [inlined]
 [3] add(ctx::Pkg.Types.Context, pkgs::Vector{Pkg.Types.PackageSpec}; preserve::Pkg.Types.PreserveLevel, platform::Base.BinaryPlatforms.Platform, target::Symbol, kwargs::@Kwargs{io::Pkg.UnstableIO})
   @ Pkg.API ~/.julia/juliaup/julia-nightly/share/julia/stdlib/v1.12/Pkg/src/API.jl:306
 [4] add(pkgs::Vector{Pkg.Types.PackageSpec}; io::Pkg.UnstableIO, kwargs::@Kwargs{})
   @ Pkg.API ~/.julia/juliaup/julia-nightly/share/julia/stdlib/v1.12/Pkg/src/API.jl:159
 [5] add(pkgs::Vector{Pkg.Types.PackageSpec})
   @ Pkg.API ~/.julia/juliaup/julia-nightly/share/julia/stdlib/v1.12/Pkg/src/API.jl:148
 [6] top-level scope
   @ none:1
 [7] eval
   @ ./boot.jl:432 [inlined]
 [8] exec_options(opts::Base.JLOptions)
   @ Base ./client.jl:291
 [9] _start()
   @ Base ./client.jl:533

Works on 1.10, broken on 1.11 and nightly.