Do not print exceptions for non ERROR events (#347)

## Changes
Adds a check to not print exceptions trace for dlt events with a level <
ERROR

## Tests
Unit test

bundle/run/progress/pipeline.go

@@ -9,6 +9,15 @@ import (
 	"github.com/databricks/databricks-sdk-go/service/pipelines"
 )
 
+// The dlt backend computes events for pipeline runs which are accessable through
+// the 2.0/pipelines/{pipeline_id}/events API
+//
+// There are 4 levels for these events: ("ERROR", "WARN", "INFO", "METRICS")
+//
+// Here's short introduction to a few important events we display on the console:
+//
+// 1. `update_progress`: A state transition occured for the entire pipeline update
+// 2. `flow_progress`: A state transition occured for a single flow in the pipeine
 type ProgressEvent pipelines.PipelineEvent
 
 func (event *ProgressEvent) String() string {
@@ -21,8 +30,8 @@ func (event *ProgressEvent) String() string {
 	result.WriteString(event.Level.String() + " ")
 	result.WriteString(fmt.Sprintf(`"%s"`, event.Message))
 
-	// construct error string
+	// construct error string if level=`Error`
-	if event.Error != nil {
+	if event.Level == pipelines.EventLevelError && event.Error != nil {
 		for _, exception := range event.Error.Exceptions {
 			result.WriteString(fmt.Sprintf("\n%s", exception.Message))
 		}

bundle/run/progress/pipeline_test.go

@@ -55,3 +55,24 @@ func TestUpdateErrorEventToString(t *testing.T) {
 	}
 	assert.Equal(t, "2023-03-27T23:30:36.122Z update_progress ERROR \"failed to update pipeline\"\nparsing error", event.String())
 }
+
+func TestUpdateErrorIgnoredForWarnEvents(t *testing.T) {
+	event := ProgressEvent{
+		EventType: "update_progress",
+		Message:   "failed to update pipeline",
+		Level:     pipelines.EventLevelWarn,
+		Origin: &pipelines.Origin{
+			FlowName:     "my_flow",
+			PipelineName: "my_pipeline",
+		},
+		Timestamp: "2023-03-27T23:30:36.122Z",
+		Error: &pipelines.ErrorDetail{
+			Exceptions: []pipelines.SerializedException{
+				{
+					Message: "THIS IS IGNORED",
+				},
+			},
+		},
+	}
+	assert.Equal(t, "2023-03-27T23:30:36.122Z update_progress WARN \"failed to update pipeline\"", event.String())
+}