fix: fixes nil pointer when message is null (#3012)

internal/docker/event_generator.go

@@ -178,8 +178,13 @@ func createEvent(message string, streamType StdType) *LogEvent {
 						}
 					}
 				} else {
-					logEvent.Message = data
+					if data == nil {
+						logEvent.Message = ""
+					} else {
+						logEvent.Message = data
+					}
 				}
+
 			} else if data, err := ParseLogFmt(message); err == nil {
 				logEvent.Message = data
 			}

internal/docker/event_generator_test.go

@@ -136,6 +136,15 @@ func Test_createEvent(t *testing.T) {
 				Message: "sample text with=equal sign",
 			},
 		},
+		{
+			name: "null message",
+			args: args{
+				message: "2020-05-13T18:55:37.772853839Z null",
+			},
+			want: &LogEvent{
+				Message: "",
+			},
+		},
 	}
 
 	for _, tt := range tests {

internal/docker/level_guesser.go

@@ -46,6 +46,9 @@ func guessLogLevel(logEvent *LogEvent) string {
 		}
 
 	case *orderedmap.OrderedMap[string, any]:
+		if value == nil {
+			return ""
+		}
 		if level, ok := value.Get("level"); ok {
 			if level, ok := level.(string); ok {
 				return strings.ToLower(level)
@@ -53,6 +56,9 @@ func guessLogLevel(logEvent *LogEvent) string {
 		}
 
 	case *orderedmap.OrderedMap[string, string]:
+		if value == nil {
+			return ""
+		}
 		if level, ok := value.Get("level"); ok {
 			return strings.ToLower(level)
 		}

internal/docker/level_guesser_test.go

@@ -1,12 +1,14 @@
 package docker
 
 import (
+	"encoding/json"
 	"testing"
 
 	orderedmap "github.com/wk8/go-ordered-map/v2"
 )
 
 func TestGuessLogLevel(t *testing.T) {
+	var nilOrderedMap *orderedmap.OrderedMap[string, any]
 	tests := []struct {
 		input    any
 		expected string
@@ -43,15 +45,17 @@ func TestGuessLogLevel(t *testing.T) {
 				orderedmap.Pair[string, any]{Key: "level", Value: "info"},
 			),
 		), "info"},
+		{nilOrderedMap, ""},
+		{nil, ""},
 	}
 
 	for _, test := range tests {
-		logEvent := &LogEvent{
-			Message: test.input,
-		}
-		if level := guessLogLevel(logEvent); level != test.expected {
-			t.Errorf("guessLogLevel(%s) = %s, want %s", test.input, level, test.expected)
-		}
+		name, _ := json.Marshal(test.input)
+		t.Run(string(name), func(t *testing.T) {
+			actual := guessLogLevel(&LogEvent{Message: test.input})
+			if actual != test.expected {
+				t.Errorf("Expected %s, got %s", test.expected, actual)
+			}
+		})
 	}
-
 }