Fix http_client input connect bug

`h.codecCtor.Create` will return a `*service.OwnedScanner`, but
`h.codec` has type `codec.DeprecatedFallbackStream`, so if we get
an error from `h.codecCtor.Create`, the `h.codec != nil` check in
`Connect` will be true, so Benthos will think the input is
connected. This can happen if the codec specification isn't
compatible with the received data.

Signed-off-by: Mihai Todor <[email protected]>

internal/impl/io/input_http_client.go

@@ -183,6 +183,7 @@ func (h *httpClientInput) Connect(ctx context.Context) (err error) {
 		return nil
 	}, service.NewScannerSourceDetails()); err != nil {
 		res.Body.Close()
+		h.codec = nil
 		return err
 	}
 	return nil