Do not fail the planning phase if the custom template name specified in the custom policy assignment is not found

Initially this check was added as the custom template creation via TMC TF provider was not supported. Now since the provider supports creation of the custom template removing this check,
to let user create the custom template and assign it to custom policy on the fly.

Signed-off-by: Ramya Bangera <bangerar@vmware.com>

Author: ramya-bangera

internal/resources/policy/kind/custom/recipe/tmc_custom_schema.go

@@ -20,6 +20,7 @@ import (
 	policyrecipecustomcommonmodel "github.com/vmware/terraform-provider-tanzu-mission-control/internal/models/policy/recipe/custom/common"
 	recipemodels "github.com/vmware/terraform-provider-tanzu-mission-control/internal/models/recipe"
 	"github.com/vmware/terraform-provider-tanzu-mission-control/internal/resources/policy/kind/common"
+	clienterrors "github.com/vmware/terraform-provider-tanzu-mission-control/internal/client/errors"
 )
 
 var TMCCustomSchema = &schema.Schema{
@@ -117,7 +118,11 @@ func ValidateCustomRecipe(config authctx.TanzuContext, customRecipe map[string]i
 	recipeData, err := config.TMCConnection.RecipeResourceService.RecipeResourceServiceGet(recipeModel)
 
 	if err != nil {
-		errMessages = append(errMessages, err.Error())
+		// NOTE: If error is 404 not found then do not fail the planning. This fix ensures that if user tries to create the new custom template
+		// and assign the same template to the custom policy in a single terraform apply operation will be able to proceed, instead of failing in the planning phase.
+		if !clienterrors.IsNotFoundError(err) {
+			errMessages = append(errMessages, err.Error())
+		}
 	} else {
 		errs := ValidateRecipeParameters(recipeData.Recipe.Spec.InputSchema, customRecipe[ParametersKey].(string))