Improve error messages, esp. when the server is running

* Add file context to minifier errors when publishing
* Misc fixes (see issues)
* Allow custom server error template in layouts/server/error.html

To get to this, this commit also cleans up and simplifies the code surrounding errors and files. This also removes the usage of `github.com/pkg/errors`, mostly because of https://github.com/pkg/errors/issues/223 -- but also because most of this is now built-in to Go.

Fixes #9852
Fixes #9857
Fixes #9863

2 files changed, 5 insertions, 7 deletions

diff --git a/source/fileInfo.go b/source/fileInfo.go
index 13c4495bf..f882eb898 100644
--- a/source/fileInfo.go
+++ b/source/fileInfo.go
@@ -14,6 +14,7 @@
 package source
 
 import (
+	"fmt"
 	"path/filepath"
 	"strings"
 	"sync"
@@ -22,8 +23,6 @@ import (
 
 	"github.com/gohugoio/hugo/hugofs/files"
 
-	"github.com/pkg/errors"
-
 	"github.com/gohugoio/hugo/common/hugio"
 
 	"github.com/gohugoio/hugo/hugofs"
@@ -244,11 +243,11 @@ func (sp *SourceSpec) NewFileInfo(fi hugofs.FileMetaInfo) (*FileInfo, error) {
 	relPath := m.Path
 
 	if relPath == "" {
-		return nil, errors.Errorf("no Path provided by %v (%T)", m, m.Fs)
+		return nil, fmt.Errorf("no Path provided by %v (%T)", m, m.Fs)
 	}
 
 	if filename == "" {
-		return nil, errors.Errorf("no Filename provided by %v (%T)", m, m.Fs)
+		return nil, fmt.Errorf("no Filename provided by %v (%T)", m, m.Fs)
 	}
 
 	relDir := filepath.Dir(relPath)
diff --git a/source/filesystem.go b/source/filesystem.go
index 4d509c566..79d027c5c 100644
--- a/source/filesystem.go
+++ b/source/filesystem.go
@@ -14,11 +14,10 @@
 package source
 
 import (
+	"fmt"
 	"path/filepath"
 	"sync"
 
-	"github.com/pkg/errors"
-
 	"github.com/gohugoio/hugo/hugofs"
 )
 
@@ -49,7 +48,7 @@ func (f *Filesystem) Files() ([]File, error) {
 	f.filesInit.Do(func() {
 		err := f.captureFiles()
 		if err != nil {
-			f.filesInitErr = errors.Wrap(err, "capture files")
+			f.filesInitErr = fmt.Errorf("capture files: %w", err)
 		}
 	})
 	return f.files, f.filesInitErr