Colorbar `tickformat` cannot be specified when the colormap is `Categorical`

[barucden]

Makie version: Makie v0.21.16

I can reproduce the bug in a fresh environment.

I am using CairoMakie without GPU. My Julia version is

Julia Version 1.11.1
Commit 8f5b7ca12ad (2024-10-16 10:53 UTC)
Build Info:
  Official https://julialang.org/ release
Platform Info:
  OS: Linux (x86_64-linux-gnu)
  CPU: 8 × Intel(R) Core(TM) i7-8550U CPU @ 1.80GHz
  WORD_SIZE: 64
  LLVM: libLLVM-16.0.6 (ORCJIT, skylake)
Threads: 1 default, 0 interactive, 1 GC (on 8 virtual cores)

A MWE is:

f = Figure()
a = Axis(f[1, 1])
hm = heatmap!(a, rand(1:10, 10, 10), colormap=Makie.Categorical(:inferno))
Colorbar(f[1, 2], hm, tickformat="1")

The colorbar line results in

ERROR: MethodError: Cannot `convert` an object of type Tuple{UnitRange{Int64}, Vector{String}} to an object of type Vector{Float64}
The function `convert` exists, but no method is defined for this combination of argument types.

Closest candidates are:
  convert(::Type{Array{T, N}}, ::StaticArraysCore.SizedArray{S, T, N, N, Array{T, N}}) where {S, T, N}
   @ StaticArrays ~/.julia/packages/StaticArrays/9Yt0H/src/SizedArray.jl:88
  convert(::Type{Array{T, N}}, ::StaticArraysCore.SizedArray{S, T, N, M, TData} where {M, TData<:AbstractArray{T, M}}) where {T, S, N}
   @ StaticArrays ~/.julia/packages/StaticArrays/9Yt0H/src/SizedArray.jl:82
  convert(::Type{T}, ::T) where T
   @ Base Base.jl:126
  ...

Stacktrace:
  [1] get_tickvalues(tickvalues::Tuple{UnitRange{Int64}, Vector{String}}, vmin::Float64, vmax::Float64)
    @ Makie ~/.julia/packages/Makie/pFPBw/src/makielayout/lineaxis.jl:631
  [2] get_tickvalues(ticks::Tuple{UnitRange{Int64}, Vector{String}}, ::Function, vmin::Float64, vmax::Float64)
    @ Makie ~/.julia/packages/Makie/pFPBw/src/makielayout/lineaxis.jl:566
  [3] get_ticks(ticks::Tuple{UnitRange{…}, Vector{…}}, scale::Function, formatter::String, vmin::Float64, vmax::Float64)
    @ Makie ~/.julia/packages/Makie/pFPBw/src/makielayout/lineaxis.jl:554
  [4] get_ticks(::Nothing, ticks::Tuple{…}, scale::Function, formatter::String, vmin::Float64, vmax::Float64)
    @ Makie ~/.julia/packages/Makie/pFPBw/src/dim-converts/dim-converts.jl:70
  [5] (::Makie.var"#1611#1625"{…})(::Tuple{…}, ::Nothing, limits::Tuple{…}, ticks::Tuple{…}, tickformat::String, scale::Function)
    @ Makie ~/.julia/packages/Makie/pFPBw/src/makielayout/lineaxis.jl:423
  [6] invokelatest(::Any, ::Any, ::Vararg{Any}; kwargs::@Kwargs{})
    @ Base ./essentials.jl:1055
  [7] invokelatest(::Any, ::Any, ::Vararg{Any})
    @ Base ./essentials.jl:1052
  [8] (::Observables.MapCallback)(value::Any)
    @ Observables ~/.julia/packages/Observables/YdEbO/src/Observables.jl:436
  [9] #map!#238
    @ ~/.julia/packages/Makie/pFPBw/src/scenes.jl:170 [inlined]
 [10] map!
    @ ~/.julia/packages/Makie/pFPBw/src/scenes.jl:163 [inlined]
 [11] Makie.LineAxis(parent::Scene, attrs::Attributes)
    @ Makie ~/.julia/packages/Makie/pFPBw/src/makielayout/lineaxis.jl:421
 [12] #LineAxis#1587
    @ ~/.julia/packages/Makie/pFPBw/src/makielayout/lineaxis.jl:8 [inlined]
 [13] initialize_block!(cb::Colorbar)
    @ Makie ~/.julia/packages/Makie/pFPBw/src/makielayout/blocks/colorbar.jl:362
 [14] _block(T::Type{…}, fig_or_scene::Figure, args::Vector{…}, kwdict::Dict{…}, bbox::Nothing; kwdict_complete::Bool)
    @ Makie ~/.julia/packages/Makie/pFPBw/src/makielayout/blocks.jl:371
 [15] _block
    @ ~/.julia/packages/Makie/pFPBw/src/makielayout/blocks.jl:291 [inlined]
 [16] #_block#1436
    @ ~/.julia/packages/Makie/pFPBw/src/makielayout/blocks.jl:259 [inlined]
 [17] _block(::Type{Colorbar}, ::GridPosition; kwargs::@Kwargs{colormap::Makie.ColorMapping{…}, tickformat::String})
    @ Makie ~/.julia/packages/Makie/pFPBw/src/makielayout/blocks.jl:253
 [18] _block
    @ ~/.julia/packages/Makie/pFPBw/src/makielayout/blocks.jl:246 [inlined]
 [19] #_#1434
    @ ~/.julia/packages/Makie/pFPBw/src/makielayout/blocks.jl:237 [inlined]
 [20] Colorbar(fig_or_scene::GridPosition, plot::Heatmap{Tuple{…}}; kwargs::@Kwargs{tickformat::String})
    @ Makie ~/.julia/packages/Makie/pFPBw/src/makielayout/blocks/colorbar.jl:108
 [21] top-level scope
    @ REPL[20]:1

Changing the colormap to (continuous) :inferno makes the error go away, and so does removing the tickformat argument.

[barucden]

Related to #3686