fix: warn if the operating point given to linearization_function is empty.

Author: AayushSabharwal

src/linearization.jl

@@ -42,8 +42,12 @@ function linearization_function(sys::AbstractSystem, inputs,
         eval_expression = false, eval_module = @__MODULE__,
         warn_initialize_determined = true,
         guesses = Dict(),
+        warn_empty_op = true,
         kwargs...)
     op = Dict(op)
+    if isempty(op)
+        @warn "An empty operating point was passed to `linearization_function`. An operating point containing the variables that will be changed in `linearize` should be provided. Disable this warning by passing `warn_empty_op = false`."
+    end
     inputs isa AbstractVector || (inputs = [inputs])
     outputs isa AbstractVector || (outputs = [outputs])
     inputs = mapreduce(vcat, inputs; init = []) do var

test/downstream/linearize.jl

@@ -337,3 +337,11 @@ end
     @test_nowarn linearize(
         tank_noi, [md_i], [h]; op = Dict(m => m_ss, md_i => 2, ρ => A / K, A => 5))
 end
+
+@testset "Warn on empty operating point" begin
+    @named tank_noi = Tank_noi()
+    @unpack md_i, h, m = tank_noi
+    m_ss = 2.4000000003229878
+    @test_warn ["empty operating point", "warn_empty_op"] linearize(
+        tank_noi, [md_i], [h]; p = [md_i => 1.0])
+end