_varmap_to_vars can lead to InexactError

[david-pl]

The type inference of _varmap_to_vars depends on the order of variables in the varmap. If the example_val happens to be real, but there are also complex values in the varmap, an InexactError is thrown. This can happen e.g. when having a complex u, but passing in real parameters (at least that was my use-case).

using ModelingToolkit
using ModelingToolkit: _varmap_to_vars

@parameters t a b
@variables c(t)::Complex
varmap = Dict(a=>1,b=>1,c=>1im)
varlist = [c]
_varmap_to_vars(varmap, varlist)