fix some lint warnings/recommendations

Makefile

@@ -29,6 +29,8 @@ CC_OUTPUT_TPL     := ${BUILDDIR}/bin/{{.Dir}}.{{.OS}}-{{.Arch}}
 # some exported vars (pre-configure go build behavior)
 export GO111MODULE=on
 export CGO_ENABLED=0
+# unsure toolchains are not automatically downloaded/upgraded
+export GOTOOLCHAIN=local
 ## enable go 1.21 loopvar "experiment"
 export GOEXPERIMENT=loopvar
 export GOBIN

pkg/camo/helpers_test.go

@@ -6,6 +6,7 @@ package camo
 
 import (
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"net/http"
@@ -123,7 +124,7 @@ func (r *Tuple[A, B]) UnmarshalJSON(p []byte) error {
 			return err
 		}
 		if s != "" {
-			err := fmt.Errorf(s)
+			err := errors.New(s)
 			r.b = err.(B)
 		}
 	} else {

pkg/htrie/htrie.go

@@ -252,7 +252,8 @@ func (dt *URLMatcher) walkFind(s string) []*URLMatcher {
 			continue
 		}
 
-		if curnode.subtrees == nil || len(curnode.subtrees) == 0 {
+		// len(nil) == 0, so no need to check twice
+		if len(curnode.subtrees) == 0 {
 			break
 		}