Can't print slices of orthogonal polynomials

[DanielVandH]

While the following variables can be defined, printing them to REPL errors:

using ClassicalOrthogonalPolynomials
Chebyshev()[0.3, :] # errors when printing
Jacobi(0.0, 0.0)[0.3, :] # errors when printing
Laguerre(0)[0.3, :] # errors when printing
# etc

with errors like

julia> Chebyshev()[0.3, :]
ℵ₀-element view(::ChebyshevT{Float64}, 0.3, :) with eltype Float64 with indices OneToInf():
ERROR: MethodError: no method matching isassigned(::ChebyshevT{Float64}, ::Float64, ::Int64)

Closest candidates are:
  isassigned(::Array, ::Int64...)
   @ Base array.jl:266
  isassigned(::LinearAlgebra.UnitLowerTriangular, ::Int64, ::Int64)
   @ LinearAlgebra C:\Users\User\.julia\juliaup\julia-1.10.3+0.x64.w64.mingw32\share\julia\stdlib\v1.10\LinearAlgebra\src\triangular.jl:226
  isassigned(::Base.ReshapedArray{T, N}, ::Int64...) where {T, N}
   @ Base reshapedarray.jl:235
  ...

Stacktrace:
  [1] isassigned
    @ .\subarray.jl:362 [inlined]
  [2] isassigned(::SubArray{Float64, 1, ChebyshevT{Float64}, Tuple{Float64, Base.Slice{InfiniteArrays.OneToInf{Int64}}}, false}, ::Int64, ::Int64)
    @ Base .\multidimensional.jl:1575
  [3] alignment(io::IOContext{Base.TTY}, X::AbstractVecOrMat, rows::Vector{Int64}, cols::Vector{Int64}, cols_if_complete::Int64, cols_otherwise::Int64, sep::Int64, ncols::Int64)
    @ Base .\arrayshow.jl:68
  [4] _print_matrix(io::IOContext{Base.TTY}, X::AbstractVecOrMat, pre::String, sep::String, post::String, hdots::String, vdots::String, ddots::String, hmod::Int64, vmod::Int64, rowsA::InfiniteArrays.InfUnitRange{Int64}, colsA::UnitRange{Int64})
    @ Base .\arrayshow.jl:207
  [5] print_matrix(io::IOContext{Base.TTY}, X::SubArray{Float64, 1, ChebyshevT{Float64}, Tuple{Float64, Base.Slice{InfiniteArrays.OneToInf{Int64}}}, false}, pre::String, sep::String, post::String, hdots::String, vdots::String, ddots::String, hmod::Int64, vmod::Int64)
    @ Base .\arrayshow.jl:171
  [6] print_matrix
    @ .\arrayshow.jl:171 [inlined]
  [7] print_array
    @ .\arrayshow.jl:358 [inlined]
  [8] show(io::IOContext{Base.TTY}, ::MIME{Symbol("text/plain")}, X::SubArray{Float64, 1, ChebyshevT{Float64}, Tuple{Float64, Base.Slice{InfiniteArrays.OneToInf{Int64}}}, false})
    @ Base .\arrayshow.jl:399
  [9] (::REPL.var"#55#56"{REPL.REPLDisplay{REPL.LineEditREPL}, MIME{Symbol("text/plain")}, Base.RefValue{Any}})(io::Any)
    @ REPL C:\Users\User\.julia\juliaup\julia-1.10.3+0.x64.w64.mingw32\share\julia\stdlib\v1.10\REPL\src\REPL.jl:273
 [10] with_repl_linfo(f::Any, repl::REPL.LineEditREPL)
    @ REPL C:\Users\User\.julia\juliaup\julia-1.10.3+0.x64.w64.mingw32\share\julia\stdlib\v1.10\REPL\src\REPL.jl:569
 [11] display(d::REPL.REPLDisplay, mime::MIME{Symbol("text/plain")}, x::Any)
    @ REPL C:\Users\User\.julia\juliaup\julia-1.10.3+0.x64.w64.mingw32\share\julia\stdlib\v1.10\REPL\src\REPL.jl:259
 [12] display(d::REPL.REPLDisplay, x::Any)
    @ REPL C:\Users\User\.julia\juliaup\julia-1.10.3+0.x64.w64.mingw32\share\julia\stdlib\v1.10\REPL\src\REPL.jl:278
 [13] display(x::Any)
    @ Base.Multimedia .\multimedia.jl:340
 [14] #invokelatest#2
    @ .\essentials.jl:892 [inlined]
 [15] invokelatest
    @ .\essentials.jl:889 [inlined]
 [16] (::VSCodeServer.var"#69#74"{Bool, Bool, Bool, Module, String, Int64, Int64, String, VSCodeServer.ReplRunCodeRequestParams})()
    @ VSCodeServer c:\Users\User\.vscode\extensions\julialang.language-julia-1.79.2\scripts\packages\VSCodeServer\src\eval.jl:237
 [17] withpath(f::VSCodeServer.var"#69#74"{Bool, Bool, Bool, Module, String, Int64, Int64, String, VSCodeServer.ReplRunCodeRequestParams}, path::String)
    @ VSCodeServer c:\Users\User\.vscode\extensions\julialang.language-julia-1.79.2\scripts\packages\VSCodeServer\src\repl.jl:276
 [18] (::VSCodeServer.var"#68#73"{Bool, Bool, Bool, Module, String, Int64, Int64, String, VSCodeServer.ReplRunCodeRequestParams})()
    @ VSCodeServer c:\Users\User\.vscode\extensions\julialang.language-julia-1.79.2\scripts\packages\VSCodeServer\src\eval.jl:179
 [19] hideprompt(f::VSCodeServer.var"#68#73"{Bool, Bool, Bool, Module, String, Int64, Int64, String, VSCodeServer.ReplRunCodeRequestParams})
    @ VSCodeServer c:\Users\User\.vscode\extensions\julialang.language-julia-1.79.2\scripts\packages\VSCodeServer\src\repl.jl:38
 [20] (::VSCodeServer.var"#67#72"{Bool, Bool, Bool, Module, String, Int64, Int64, String, VSCodeServer.ReplRunCodeRequestParams})()
    @ VSCodeServer c:\Users\User\.vscode\extensions\julialang.language-julia-1.79.2\scripts\packages\VSCodeServer\src\eval.jl:150
 [21] with_logstate(f::Function, logstate::Any)
    @ Base.CoreLogging .\logging.jl:515
 [22] with_logger
    @ .\logging.jl:627 [inlined]
 [23] (::VSCodeServer.var"#66#71"{VSCodeServer.ReplRunCodeRequestParams})()
    @ VSCodeServer c:\Users\User\.vscode\extensions\julialang.language-julia-1.79.2\scripts\packages\VSCodeServer\src\eval.jl:263
 [24] #invokelatest#2
    @ .\essentials.jl:892 [inlined]
 [25] invokelatest(::Any)
    @ Base .\essentials.jl:889
 [26] (::VSCodeServer.var"#64#65")()
    @ VSCodeServer c:\Users\User\.vscode\extensions\julialang.language-julia-1.79.2\scripts\packages\VSCodeServer\src\eval.jl:34

Judging from the error, would it be reasonable to define

using ClassicalOrthogonalPolynomials: OrthogonalPolynomial
Base.isassigned(P::OrthogonalPolynomial, x, n) = (x ∈ axes(P, 1)) && (n ∈ axes(P, 2))

The printing works with this:

julia> Chebyshev()[0.3, :]' # transposing to reduce vertical space
1×ℵ₀ adjoint(view(::ChebyshevT{Float64}, 0.3, :)) with eltype Float64 with indices Base.OneTo(1)×OneToInf():
 1.0  0.3  -0.82  -0.792  0.3448  0.99888  0.254528  -0.846163  -0.762226  0.388828  …

julia> Jacobi(0.0, 0.0)[0.3, :]'
1×ℵ₀ adjoint(view(::Jacobi{Float64}, 0.3, :)) with eltype Float64 with indices Base.OneTo(1)×OneToInf():
 1.0  0.3  -0.365  -0.3825  0.0729375  0.345386  0.129181  -0.224073  -0.239075  …

julia> Laguerre(0)[0.3, :]'
1×ℵ₀ adjoint(view(::Laguerre{Float64}, 0.3, :)) with eltype Float64 with indices Base.OneTo(1)×OneToInf():
 1.0  0.7  0.445  0.2305  0.0523375  -0.0933327  -0.210058  -0.301106  -0.369481  …