Using types on input variables cause `ERROR: AssertionError: issorted(input_idxs)`

[bradcarman]

Take the following...

using ModelingToolkit
using ModelingToolkit: t_nounits as t, D_nounits as D

pars = @parameters begin
    a = 1
    b = 2
end

vars = @variables begin
    x(t)=0
    y(t)=0

    xi(t)::Int, [input=true]
    yi(t), [input=true]
end

eqs = [
    D(x) ~ a*xi
    D(y) ~ b*yi
]

@mtkcompile sys = System(eqs, t, vars, pars) inputs=[xi,yi]

Gives...

ERROR: AssertionError: issorted(input_idxs)
Stacktrace:
 [1] complete(sys::System; split::Bool, flatten::Bool, add_initial_parameters::Bool)
   @ ModelingToolkit c:\Users\bradl\.julia\packages\ModelingToolkit\b28X4\src\systems\abstractsystem.jl:689
 [2] mtkcompile(sys::System; additional_passes::Vector{…}, simplify::Bool, split::Bool, allow_symbolic::Bool, allow_parameter::Bool, conservative::Bool, fully_determined::Bool, inputs::Vector{…}, outputs::Vector{…}, disturbance_inputs::Vector{…}, kwargs::@Kwargs{})
   @ ModelingToolkit C:\Users\bradl\.julia\packages\ModelingToolkit\b28X4\src\systems\systems.jl:53
 [3] top-level scope
   @ C:\Users\bradl\.julia\packages\ModelingToolkit\b28X4\src\systems\abstractsystem.jl:2392

Note: this error occurs because xi is specified as Int type and is defined earlier then yi. Switching the order (i.e. making yi::Int and xi assumed Float64) does not produce the error.

Also this bug is avoided by using the split=false option for mtkcompile