Fixed seg fault when specifying environment key for tasks (#1443)

## Changes
Fixed seg fault when specifying environment key for tasks

bundle/artifacts/artifacts.go

@@ -150,6 +150,10 @@ func uploadArtifact(ctx context.Context, b *bundle.Bundle, a *config.Artifact, u
 
 			for i := range job.Environments {
 				env := &job.Environments[i]
+				if env.Spec == nil {
+					continue
+				}
+
 				for j := range env.Spec.Dependencies {
 					lib := env.Spec.Dependencies[j]
 					if isArtifactMatchLibrary(f, lib, b) {

bundle/libraries/libraries.go

@@ -30,6 +30,10 @@ func FindAllEnvironments(b *bundle.Bundle) map[string]([]jobs.JobEnvironment) {
 
 func isEnvsWithLocalLibraries(envs []jobs.JobEnvironment) bool {
 	for _, e := range envs {
+		if e.Spec == nil {
+			continue
+		}
+
 		for _, l := range e.Spec.Dependencies {
 			if IsEnvironmentDependencyLocal(l) {
 				return true

bundle/libraries/match.go

@@ -62,6 +62,10 @@ func validateTaskLibraries(libs []compute.Library, b *bundle.Bundle) error {
 
 func validateEnvironments(envs []jobs.JobEnvironment, b *bundle.Bundle) error {
 	for _, env := range envs {
+		if env.Spec == nil {
+			continue
+		}
+
 		for _, dep := range env.Spec.Dependencies {
 			matches, err := filepath.Glob(filepath.Join(b.RootPath, dep))
 			if err != nil {

bundle/tests/enviroment_key_test.go

@@ -1,12 +1,23 @@
 package config_tests
 
 import (
+	"context"
 	"testing"
 
+	"github.com/databricks/cli/bundle"
+	"github.com/databricks/cli/bundle/libraries"
 	"github.com/stretchr/testify/require"
 )
 
 func TestEnvironmentKeySupported(t *testing.T) {
 	_, diags := loadTargetWithDiags("./python_wheel/environment_key", "default")
 	require.Empty(t, diags)
 }
+
+func TestEnvironmentKeyProvidedAndNoPanic(t *testing.T) {
+	b, diags := loadTargetWithDiags("./environment_key_only", "default")
+	require.Empty(t, diags)
+
+	diags = bundle.Apply(context.Background(), b, libraries.ValidateLocalLibrariesExist())
+	require.Empty(t, diags)
+}

bundle/tests/environment_key_only/databricks.yml

@@ -0,0 +1,16 @@
+bundle:
+  name: environment_key_only
+
+resources:
+  jobs:
+    test_job:
+      name: "My Wheel Job"
+      tasks:
+        - task_key: TestTask
+          existing_cluster_id: "0717-132531-5opeqon1"
+          python_wheel_task:
+            package_name: "my_test_code"
+            entry_point: "run"
+          environment_key:  "test_env"
+      environments:
+        - environment_key:  "test_env"