fix: harden signature cache publication

opt_device.go

@@ -1,17 +1,23 @@
 package acp
 
+import "fmt"
+
 type deviceOption struct {
 	linear  bool
 	threads int
 }
 
-func (do *deviceOption) check() {
+func (do *deviceOption) check() error {
+	if do.threads < 0 {
+		return fmt.Errorf("device threads cannot be negative, threads=%d", do.threads)
+	}
 	if do.threads == 0 {
 		do.threads = 8
 	}
 	if do.linear {
 		do.threads = 1
 	}
+	return nil
 }
 
 type DeviceOption func(*deviceOption) *deviceOption