fix panic on missing formatter in console_exporter.ProcessorOptions

pkg/exporters/console_exporter/console_exporter.go

@@ -76,7 +76,8 @@ func NewProcessor(opts ProcessorOptions) trace.SpanProcessor {
 	if opts.TraceFormatter != nil {
 		formatter = *opts.TraceFormatter
 	} else {
-		formatter = TraceFormatter(nil)
+		fmt := NewPrettyMultilineFormatter()
+		formatter = fmt
 	}
 	if opts.FilterOnLevel != 0 {
 		lvl = opts.FilterOnLevel