Error message improvement for value(Array of NLexpression)

[anastasianikolako]

When calling value(u) where u is an array of variables the following error shows up

julia> value(u)
ERROR: `JuMP.value` is not defined for collections of JuMP types. Use Julia's broadcast syntax instead: `JuMP.value.(x)`.
Stacktrace:
 [1] error(s::String)
   @ Base .\error.jl:33
 [2] value(#unused#::Matrix{VariableRef})
   @ JuMP C:\Users\user\.julia\packages\JuMP\Xrr7O\src\variables.jl:1204

This error is helpful.

On the other hand, when calling value(u) where u is an array of nonlinear expressions the error is

ERROR: LoadError: MethodError: no method matching value(::Matrix{NonlinearExpression})

This is not as helpful as it does not say that value. should be used instead.

[odow]

Thanks for raising the issue.

There is this error:

JuMP.jl/src/variables.jl

Lines 1230 to 1235 in 2871a06

	function value(::AbstractArray{<:AbstractJuMPScalar})
	return error(
	"`JuMP.value` is not defined for collections of JuMP types. Use" *
	" Julia's broadcast syntax instead: `JuMP.value.(x)`.",
	)
	end

but it looks like we need to make NonlinearExpression <: AbstractJuMPScalar:

JuMP.jl/src/JuMP.jl

Line 1373 in 5bdec26

struct NonlinearExpression