fix: address code review feedback (imports, typo, perf)

Signed-off-by: devmanishofficial <devmanishofficial@gmail.com>

Author: DEVMANISHOFFL

go/MIDDLEWARE.md

@@ -13,11 +13,9 @@ package main
 
 import (
 	"context"
-	"fmt"
 	"log"
 
 	"github.com/firebase/genkit/go/core"
-	"github.com/firebase/genkit/go/genkit"
 )
 
 func MyMiddleware[In, Out, Stream any](next core.StreamingFunc[In, Out, Stream]) core.StreamingFunc[In, Out, Stream] {

go/README.md

@@ -3,4 +3,4 @@
 This package is the Go version of Genkit, a framework for building
 AI-powered apps. See: https://genkit.dev/go/docs/get-started-go
 
-- [Middleware Guide](MIDDLEWARE.md): Learn how to add logging, authentication, and custom logic to your flows.c
+- [Middleware Guide](MIDDLEWARE.md): Learn how to add logging, authentication, and custom logic to your flows.

go/core/tracing/tracing.go

@@ -410,7 +410,7 @@ type filteringExporter struct {
 }
 
 func (e *filteringExporter) ExportSpans(ctx context.Context, spans []sdktrace.ReadOnlySpan) error {
-	var genkitSpans []sdktrace.ReadOnlySpan
+	genkitSpans := make([]sdktrace.ReadOnlySpan, 0, len(spans))
 	for _, span := range spans {
 		if isGenkitSpan(span) {
 			genkitSpans = append(genkitSpans, span)