fix: linting pointer error when template name is invalid (argoproj#14896)

Signed-off-by: jmeridth <jmeridth@gmail.com>

Author: jmeridth

test/e2e/cli_test.go

@@ -706,6 +706,12 @@ func (s *CLISuite) TestWorkflowLint() {
 			assert.Contains(t, output, "no linting errors found")
 		})
 	})
+	s.Run("LintFileEmptyTemplateSteps", func() {
+		s.Given().RunCli([]string{"lint", "smoke/empty-template-steps.yaml"}, func(t *testing.T, output string, err error) {
+			require.NoError(t, err)
+			assert.Contains(t, output, "no linting errors found")
+		})
+	})
 	s.Run("LintFileEmptyParamDAG", func() {
 		s.Given().RunCli([]string{"lint", "expectedfailures/empty-parameter-dag.yaml"}, func(t *testing.T, output string, err error) {
 			require.EqualError(t, err, "exit status 1")
@@ -718,6 +724,12 @@ func (s *CLISuite) TestWorkflowLint() {
 			assert.Contains(t, output, "templates.abc.steps[0].a templates.whalesay inputs.parameters.message was not supplied")
 		})
 	})
+	s.Run("LintFileMisreferenceTemplate", func() {
+		s.Given().RunCli([]string{"lint", "expectedfailures/misreference-template-name.yaml"}, func(t *testing.T, output string, err error) {
+			require.EqualError(t, err, "exit status 1")
+			assert.Contains(t, output, "templates.steps-with-misreference.steps[1].hello2 template name 'hell0' undefined")
+		})
+	})
 	s.Run("LintFileWithTemplate", func() {
 		s.Given().
 			WorkflowTemplate("@smoke/workflow-template-whalesay-template.yaml").

test/e2e/expectedfailures/misreference-template-name.yaml

@@ -0,0 +1,32 @@
+apiVersion: argoproj.io/v1alpha1
+kind: Workflow
+metadata:
+  generateName: steps-with-misreference-
+spec:
+  podMetadata:
+    labels:
+      test: steps-with-misreference
+  podPriorityClassName: lowest
+  entrypoint: steps-with-misreference
+  templates:
+    - name: steps-with-misreference
+      steps:
+        - - name: hello1
+            template: hello
+            arguments:
+              parameters:
+                - name: message
+                  value: "hello1"
+        - - name: hello2
+            template: hell0
+            arguments:
+              parameters:
+                - name: message
+                  value: "hello2"
+    - name: hello
+      inputs:
+        parameters:
+          - name: message
+      container:
+        image: argoproj/argosay:v2
+        args: ["echo", "{{inputs.parameters.message}}"]

test/e2e/smoke/empty-template-steps.yaml

@@ -0,0 +1,33 @@
+apiVersion: argoproj.io/v1alpha1
+kind: Workflow
+metadata:
+  generateName: empty-array-in-steps
+spec:
+  podMetadata:
+    labels:
+      test: empty-array-in-steps
+  podPriorityClassName: lowest
+  entrypoint: steps-with-empty-array
+  templates:
+    - name: steps-with-empty-array
+      steps:
+        - - name: hello1
+            template: hello
+            arguments:
+              parameters:
+                - name: message
+                  value: "hello1"
+        - []
+        - - name: hello2
+            template: hello
+            arguments:
+              parameters:
+                - name: message
+                  value: "hello2"
+    - name: hello
+      inputs:
+        parameters:
+          - name: message
+      container:
+        image: argoproj/argosay:v2
+        args: ["echo", "{{inputs.parameters.message}}"]

workflow/templateresolution/context.go

@@ -110,13 +110,13 @@ func (tplCtx *TemplateContext) GetTemplateByName(ctx context.Context, name strin
 	tplCtx.log.WithField("name", name).Debug(ctx, "Getting the template by name")
 
 	tmpl := tplCtx.tmplBase.GetTemplateByName(name)
+	if tmpl == nil {
+		return nil, errors.Errorf(errors.CodeNotFound, "template %s not found", name)
+	}
 
 	podMetadata := tplCtx.tmplBase.GetPodMetadata()
 	tplCtx.addPodMetadata(podMetadata, tmpl)
 
-	if tmpl == nil {
-		return nil, errors.Errorf(errors.CodeNotFound, "template %s not found", name)
-	}
 	return tmpl.DeepCopy(), nil
 }