fs: fix confusing "didn't find section in config file" error

This change decorates the error with the section name not found which
will hopefully save user confusion.

Fixes #8170

backend/googlephotos/googlephotos_test.go

@@ -2,6 +2,7 @@ package googlephotos
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"io"
 	"net/http"
@@ -35,7 +36,7 @@ func TestIntegration(t *testing.T) {
 		*fstest.RemoteName = "TestGooglePhotos:"
 	}
 	f, err := fs.NewFs(ctx, *fstest.RemoteName)
-	if err == fs.ErrorNotFoundInConfigFile {
+	if errors.Is(err, fs.ErrorNotFoundInConfigFile) {
 		t.Skipf("Couldn't create google photos backend - skipping tests: %v", err)
 	}
 	require.NoError(t, err)

fs/cache/cache_test.go

@@ -131,7 +131,7 @@ func TestPutErr(t *testing.T) {
 	assert.Equal(t, 1, Entries())
 
 	fNew, err := GetFn(context.Background(), "mock:/", create)
-	require.Equal(t, fs.ErrorNotFoundInConfigFile, err)
+	require.True(t, errors.Is(err, fs.ErrorNotFoundInConfigFile))
 	require.Equal(t, f, fNew)
 
 	assert.Equal(t, 1, Entries())
@@ -141,7 +141,7 @@ func TestPutErr(t *testing.T) {
 	PutErr("mock:/file.txt", f, fs.ErrorNotFoundInConfigFile)
 
 	fNew, err = GetFn(context.Background(), "mock:/file.txt", create)
-	require.Equal(t, fs.ErrorNotFoundInConfigFile, err)
+	require.True(t, errors.Is(err, fs.ErrorNotFoundInConfigFile))
 	require.Equal(t, f, fNew)
 
 	assert.Equal(t, 1, Entries())

fs/newfs.go

@@ -6,6 +6,7 @@ import (
 	"context"
 	"crypto/md5"
 	"encoding/base64"
+	"fmt"
 	"os"
 	"path/filepath"
 	"strings"
@@ -104,7 +105,7 @@ func ParseRemote(path string) (fsInfo *RegInfo, configName, fsPath string, conne
 			m := ConfigMap("", nil, configName, parsed.Config)
 			fsName, ok = m.Get("type")
 			if !ok {
-				return nil, "", "", nil, ErrorNotFoundInConfigFile
+				return nil, "", "", nil, fmt.Errorf("%w (%q)", ErrorNotFoundInConfigFile, configName)
 			}
 		}
 	} else {

fs/rc/rcserver/rcserver_test.go

@@ -358,7 +358,7 @@ func TestRemoteServing(t *testing.T) {
 			URL:    "[notfoundremote:]/",
 			Status: http.StatusInternalServerError,
 			Expected: `{
-	"error": "failed to make Fs: didn't find section in config file",
+	"error": "failed to make Fs: didn't find section in config file (\"notfoundremote\")",
 	"input": null,
 	"path": "/",
 	"status": 500

fstest/fstests/fstests.go

@@ -459,7 +459,7 @@ func Run(t *testing.T, opt *Opt) {
 	subRemoteName, subRemoteLeaf, err = fstest.RandomRemoteName(remoteName)
 	require.NoError(t, err)
 	f, err = fs.NewFs(context.Background(), subRemoteName)
-	if err == fs.ErrorNotFoundInConfigFile {
+	if errors.Is(err, fs.ErrorNotFoundInConfigFile) {
 		t.Logf("Didn't find %q in config file - skipping tests", remoteName)
 		return
 	}