Duplicate error messages on embedded form

[rgraff]

Describe the bug
I have an action that given invalid input will generate 2 errors. But when given the same input in an AshPhoenix.Form, the same invalid input will generate each error twice.

I wrote the following test to duplicate the issue in my app.

    test "should not duplicate error messages", %{
      environment: environment,
      feature: feature,
      owner: owner
    } do
      # This assertation passes. There are 2 errors: key is required, value is required
      assert {:error,
              %Ash.Error.Invalid{
                errors: [
                  %Ash.Error.Changes.Required{
                    field: :key,
                    type: :attribute,
                    resource: MyApp.Environments.FeatureVariant.String,
                    changeset: nil,
                    query: nil,
                    error_context: [],
                    vars: [],
                    path: [:variant],
                    class: :invalid
                  },
                  %Ash.Error.Changes.Required{
                    field: :value,
                    type: :attribute,
                    resource: MyApp.Environments.FeatureVariant.String,
                    changeset: nil,
                    query: nil,
                    error_context: [],
                    vars: [],
                    path: [:variant],
                    class: :invalid
                  }
                ]
              }} =
               MyApp.Environments.Feature.add_variant(
                 feature,
                 %{
                   variant: %{
                     description: "",
                     enabled: "true",
                     key: "",
                     metadata: "{}",
                     type: "string",
                     value: ""
                   }
                 },
                 actor: owner,
                 tenant: environment.organization_id
               )

      # This should be the same as above, except going AshPhoenix.Form, but there are now 4 errors.
      assert {:error,
              %{
                source: %{
                  forms: %{
                    variant: %{
                      # submit_errors does not match.
                      # I expect 2 errors, but there are 4. Each of the 2 errors is duplicated.
                      submit_errors: [value: {"is required", []}, key: {"is required", []}]
                    }
                  }
                }
              }} =
               AshPhoenix.Form.for_update(feature, :add_variant,
                 api: MyApp.Environments,
                 as: "feature",
                 forms: [
                   auto?: true
                 ],
                 actor: owner,
                 tenant: environment.organization_id
               )
               |> Phoenix.Component.to_form()
               |> AshPhoenix.Form.add_form(:variant, params: %{"type" => "string"})
               |> AshPhoenix.Form.submit(
                 params: %{
                   "variant" => %{
                     "_form_type" => "create",
                     "_persistent_id" => "0",
                     "_touched" => "_form_type,_touched,type",
                     "description" => "",
                     "enabled" => "true",
                     "key" => "",
                     "metadata" => "{}",
                     "type" => "string",
                     "value" => ""
                   }
                 }
               )
    end

To Reproduce
I can reliably reproduce this in my app. I don't have an easy way to replicate it outside of my app though.

Expected behavior
The errors should not duplicate

** Runtime
I'm on the latest Ash Versions.

Additional context
This form has an embedded form for an argument that is an embedded resource (but not a relationship). That resource is also a union of models.

[zachdaniel]

Interestinggggggg....It's hard to say what the cause is without a reproduction, but I think it's safe for us to use an Enum.uniq when generating these errors anyway. The main reason being that two error messages could theoretically be added with the same error message for the same field and we'd want to hide those anyway.

[zachdaniel]

Should be "fixed" in main. The production of duplicate errors somewhere in the process is not ideal, but this should at least fix the UX issue that you're seeing.