Make init context error message consistent with other usage

Resolves #1863 (comment)

js/modules/k6/execution/execution.go

@@ -39,7 +39,7 @@ func New() *Execution {
 func (e *Execution) GetVUStats(ctx context.Context) (map[string]interface{}, error) {
 	vuState := lib.GetState(ctx)
 	if vuState == nil {
-		return nil, errors.New("VU information can only be returned from an exported function")
+		return nil, errors.New("getting VU information in the init context is not supported")
 	}
 
 	scID, _ := vuState.GetScenarioVUID()
@@ -57,7 +57,7 @@ func (e *Execution) GetVUStats(ctx context.Context) (map[string]interface{}, err
 func (e *Execution) GetScenarioStats(ctx context.Context) (map[string]interface{}, error) {
 	ss := lib.GetScenarioState(ctx)
 	if ss == nil {
-		return nil, errors.New("scenario information can only be returned from an exported function")
+		return nil, errors.New("getting scenario information in the init context is not supported")
 	}
 
 	progress, _ := ss.ProgressFn()
@@ -79,7 +79,7 @@ func (e *Execution) GetScenarioStats(ctx context.Context) (map[string]interface{
 func (e *Execution) GetTestStats(ctx context.Context) (map[string]interface{}, error) {
 	es := lib.GetExecutionState(ctx)
 	if es == nil {
-		return nil, errors.New("test information can only be returned from an exported function")
+		return nil, errors.New("getting test information in the init context is not supported")
 	}
 
 	out := map[string]interface{}{

js/runner_test.go

@@ -2039,7 +2039,7 @@ func TestExecutionStats(t *testing.T) {
 		{"vu_err", `
 		var exec = require('k6/execution');
 		exec.getVUStats();
-		`, "VU information can only be returned from an exported function"},
+		`, "getting VU information in the init context is not supported"},
 		{"scenario_ok", `
 		var exec = require('k6/execution');
 		var sleep = require('k6').sleep;
@@ -2057,7 +2057,7 @@ func TestExecutionStats(t *testing.T) {
 		{"scenario_err", `
 		var exec = require('k6/execution');
 		exec.getScenarioStats();
-		`, "scenario information can only be returned from an exported function"},
+		`, "getting scenario information in the init context is not supported"},
 		{"test_ok", `
 		var exec = require('k6/execution');
 
@@ -2071,7 +2071,7 @@ func TestExecutionStats(t *testing.T) {
 		{"test_err", `
 		var exec = require('k6/execution');
 		exec.getTestStats();
-		`, "test information can only be returned from an exported function"},
+		`, "getting test information in the init context is not supported"},
 	}
 
 	for _, tc := range testCases {