fix: e2e: validate inputData during log postprocessing to avoid panic

Author: damdo

test/e2e/shared/common.go

@@ -312,7 +312,11 @@ func postProcessBase64LogData(dir, src, dst string) error {
 	}
 
 	// Extract second line which contains the data (first line contains the command)
-	inputStringData := strings.Split(string(inputData), "\n")[1]
+	inputDataLines := strings.Split(string(inputData), "\n")
+	if len(inputDataLines) < 2 {
+		return errors.Errorf("source file %q does not contain expected data (need at least 2 lines, got %d), input data content: %q", sourceFile, len(inputDataLines), string(inputData))
+	}
+	inputStringData := inputDataLines[1]
 
 	// Trim spaces and the $ suffix.
 	inputStringData = strings.TrimSpace(inputStringData)