common/maps: Do not return error on params dot access on incompatible types

This error was introduced in 0.56 and has shown some site breakage in the wild.

Fixes #6121

common/maps/params.go

@@ -16,8 +16,6 @@ package maps
 import (
 	"strings"
 
-	"github.com/pkg/errors"
-
 	"github.com/spf13/cast"
 )
 
@@ -72,7 +70,7 @@ func traverseNestedParams(keySegments []string, lookupFn func(key string) interf
 		v, key, owner := traverseParams(rest, m)
 		return v, key, owner, nil
 	default:
-		return nil, "", nil, errors.Errorf("unsupported Params type: %T", result)
+		return nil, "", nil, nil
 	}
 }
 

common/maps/params_test.go

@@ -22,10 +22,14 @@ import (
 func TestGetNestedParam(t *testing.T) {
 
 	m := map[string]interface{}{
+		"string":          "value",
 		"first":           1,
 		"with_underscore": 2,
 		"nested": map[string]interface{}{
 			"color": "blue",
+			"nestednested": map[string]interface{}{
+				"color": "green",
+			},
 		},
 	}
 
@@ -41,5 +45,7 @@ func TestGetNestedParam(t *testing.T) {
 	assert.Equal(1, must("First", "_", m))
 	assert.Equal(2, must("with_underscore", "_", m))
 	assert.Equal("blue", must("nested_color", "_", m))
+	assert.Equal("green", must("nested.nestednested.color", ".", m))
+	assert.Nil(must("string.name", ".", m))
 
 }

hugolib/page_test.go

@@ -1543,3 +1543,58 @@ title: Scratch Me!
 	b.AssertFileContent("public/index.html", "B: bv")
 	b.AssertFileContent("public/scratchme/index.html", "C: cv")
 }
+
+func TestPageParam(t *testing.T) {
+	t.Parallel()
+
+	b := newTestSitesBuilder(t).WithConfigFile("toml", `
+
+baseURL = "https://example.org"
+
+[params]
+[params.author]
+  name = "Kurt Vonnegut"
+
+`)
+	b.WithTemplatesAdded("index.html", `
+
+{{ $withParam := .Site.GetPage "withparam" }}
+{{ $noParam := .Site.GetPage "noparam" }}
+{{ $withStringParam := .Site.GetPage "withstringparam" }}
+
+Author page: {{ $withParam.Param "author.name" }}
+Author page string: {{ $withStringParam.Param "author.name" }}|
+Author site config:  {{ $noParam.Param "author.name" }}
+
+`,
+	)
+
+	b.WithContent("withparam.md", `
++++
+title = "With Param!"
+[author]
+  name = "Ernest Miller Hemingway"
+
++++
+
+`,
+
+		"noparam.md", `
+---
+title: "No Param!"
+---
+`, "withstringparam.md", `
++++
+title = "With string Param!"
+author = "Jo Nesbø"
+
++++
+
+`)
+	b.Build(BuildCfg{})
+
+	b.AssertFileContent("public/index.html", "Author page: Ernest Miller Hemingway")
+	b.AssertFileContent("public/index.html", "Author page string: |")
+	b.AssertFileContent("public/index.html", "Author site config:  Kurt Vonnegut")
+
+}