linting: use errors.As (errorlint)

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

Author: thaJeztah

connection.go

@@ -356,7 +356,8 @@ Loop:
 			} else {
 				debugMessage("(%p) EOF received", s)
 			}
-			if spdyErr, ok := err.(*spdy.Error); ok && spdyErr.Err == spdy.InvalidControlFrame {
+			var spdyErr *spdy.Error
+			if errors.As(err, &spdyErr) && spdyErr.Err == spdy.InvalidControlFrame {
 				_ = s.conn.Close()
 			}
 			break

spdy/spdy_test.go

@@ -280,7 +280,8 @@ func TestParseHeaderValueBlockRejectsHeaderCountOverLimit(t *testing.T) {
 	if err == nil {
 		t.Fatal("expected error for excessive header count")
 	}
-	spdyErr, ok := err.(*Error)
+	var spdyErr *Error
+	ok := errors.As(err, &spdyErr)
 	if !ok || spdyErr.Err != InvalidControlFrame {
 		t.Fatalf("unexpected error: %v", err)
 	}
@@ -300,7 +301,8 @@ func TestParseHeaderValueBlockRejectsHeaderFieldSizeOverLimit(t *testing.T) {
 	if err == nil {
 		t.Fatal("expected error for excessive header field size")
 	}
-	spdyErr, ok := err.(*Error)
+	var spdyErr *Error
+	ok := errors.As(err, &spdyErr)
 	if !ok || spdyErr.Err != InvalidControlFrame {
 		t.Fatalf("unexpected error: %v", err)
 	}
@@ -725,9 +727,9 @@ func checkZeroStreamId(t *testing.T, frame string, method string, err error) {
 		t.Errorf("%s ZeroStreamId, no error on %s", method, frame)
 		return
 	}
-	eerr := &Error{}
-	ok := errors.As(err, &eerr)
-	if !ok || eerr.Err != ZeroStreamId {
-		t.Errorf("%s ZeroStreamId, incorrect error %#v, frame %s", method, eerr, frame)
+	var spdyErr *Error
+	ok := errors.As(err, &spdyErr)
+	if !ok || spdyErr.Err != ZeroStreamId {
+		t.Errorf("%s ZeroStreamId, incorrect error %#v, frame %s", method, spdyErr, frame)
 	}
 }