Reject a standalone weight on key presence, whatever its value

edge_test.go

@@ -91,7 +91,7 @@ func TestNewErrors(t *testing.T) {
 		},
 		"an option name used as a token": {
 			map[string]string{"a": `{"format":"{weight}"}`},
-			`"weight" is an option, never a field`,
+			`"weight" is an option and can never be a field`,
 		},
 		"category name with a dot": {
 			map[string]string{"a.b": `["1"]`},

node.go

@@ -51,13 +51,11 @@ type template struct {
 func (*template) isNode() {}
 
 // compile converts parsed JSON into a node tree, validating structure up front.
-// Only a choice's items carry a weight, so a numeric one here would be inert.
+// Only a choice's items carry a weight, so one here would be inert whatever its type.
 func compile(v any) (node, error) {
 	if m, ok := v.(map[string]any); ok {
-		if w, weighted := m["weight"]; weighted {
+		if _, weighted := m["weight"]; weighted {
-			if _, isNumber := w.(float64); isNumber {
+			return nil, fmt.Errorf("weight only skews a choice's items, so it has no effect here; it is an option and can never be a field")
-				return nil, fmt.Errorf("weight only skews a choice's items, so it has no effect here")
-			}
 		}
 	}
 	return compileItem(v)

template.go

@@ -144,7 +144,7 @@ func checkTokens(format string, fields map[string]node) error {
 			}
 			if _, ok := fields[name]; !ok {
 				if isOption(name) {
-					return fmt.Errorf("token {%s}: %q is an option, never a field", t.body, name)
+					return fmt.Errorf("token {%s}: %q is an option and can never be a field", t.body, name)
 				}
 				return fmt.Errorf("token {%s}: no field %q", t.body, name)
 			}