push response item to dep_id_string sub-Dict

... when the `dep_id_string` is already present in the outer
    response Dict

This makes callbacks with multiple output referencing the same
component id update properly

The failing test added in the previous commit is also fixed here

Author: etpinard

src/handler/processors/callback.jl

@@ -20,11 +20,16 @@ function _push_to_res!(res, value, out::Vector)
     _push_to_res!.(Ref(res), value, out)
 end
 function _push_to_res!(res, value, out)
-    !(value isa NoUpdate) && push!(res,
-            dep_id_string(out.id) => Dict(
-                Symbol(out.property) => DashBase.to_dash(value)
-            )
-        )
+    if !(value isa NoUpdate)
+        id = dep_id_string(out.id)
+        prop = Symbol(out.property)
+        dashval = DashBase.to_dash(value)
+        if haskey(res, id)
+            push!(res[id], prop => dashval)
+        else
+            push!(res, id => Dict{Symbol, Any}(prop => dashval))
+        end
+    end
 end
 
 _single_element_vect(e::T) where {T} = T[e]

test/callbacks.jl

@@ -143,7 +143,8 @@ end
             Symbol("..input-two.placeholder...input-two.type.."),
             [(id = "input-two", property = "placeholder"),
              (id = "input-two", property = "type")],
-            [(value = "text",)], [])[:response] == Dict("input-two" => Dict(:type => "text"))
+            [(value = "text",)], [])[:response] == Dict("input-two" => Dict(:type => "text",
+                                                                            :placeholder => "text ??"))
 
 end
 @testset "callback! checks" begin