Create a struct with all of Hugo's config options

Primary motivation is documentation, but it will also hopefully simplify the code.

Also,

* Lower case the default output format names; this is in line with the custom ones (map keys) and how
it's treated all the places. This avoids doing `stringds.EqualFold` everywhere.

Closes #10896
Closes #10620

modules/collect.go

@@ -52,20 +52,6 @@ func IsNotExist(err error) bool {
 	return errors.Is(err, os.ErrNotExist)
 }
 
-// CreateProjectModule creates modules from the given config.
-// This is used in tests only.
-func CreateProjectModule(cfg config.Provider) (Module, error) {
-	workingDir := cfg.GetString("workingDir")
-	var modConfig Config
-
-	mod := createProjectModule(nil, workingDir, modConfig)
-	if err := ApplyProjectConfigDefaults(cfg, mod); err != nil {
-		return nil, err
-	}
-
-	return mod, nil
-}
-
 func (h *Client) Collect() (ModulesConfig, error) {
 	mc, coll := h.collect(true)
 	if coll.err != nil {
@@ -90,6 +76,9 @@ func (h *Client) Collect() (ModulesConfig, error) {
 }
 
 func (h *Client) collect(tidy bool) (ModulesConfig, *collector) {
+	if h == nil {
+		panic("nil client")
+	}
 	c := &collector{
 		Client: h,
 	}
@@ -133,6 +122,16 @@ type ModulesConfig struct {
 	GoWorkspaceFilename string
 }
 
+func (m ModulesConfig) HasConfigFile() bool {
+	for _, mod := range m.ActiveModules {
+		if len(mod.ConfigFilenames()) > 0 {
+			return true
+		}
+
+	}
+	return false
+}
+
 func (m *ModulesConfig) setActiveMods(logger loggers.Logger) error {
 	var activeMods Modules
 	for _, mod := range m.AllModules {
@@ -230,6 +229,7 @@ func (c *collector) getVendoredDir(path string) (vendoredModule, bool) {
 }
 
 func (c *collector) add(owner *moduleAdapter, moduleImport Import, disabled bool) (*moduleAdapter, error) {
+
 	var (
 		mod       *goModule
 		moduleDir string
@@ -299,7 +299,7 @@ func (c *collector) add(owner *moduleAdapter, moduleImport Import, disabled bool
 					return nil, nil
 				}
 				if found, _ := afero.Exists(c.fs, moduleDir); !found {
-					c.err = c.wrapModuleNotFound(fmt.Errorf(`module %q not found; either add it as a Hugo Module or store it in %q.`, modulePath, c.ccfg.ThemesDir))
+					c.err = c.wrapModuleNotFound(fmt.Errorf(`module %q not found in % q; either add it as a Hugo Module or store it in %q.`, modulePath, moduleDir, c.ccfg.ThemesDir))
 					return nil, nil
 				}
 			}
@@ -347,7 +347,7 @@ func (c *collector) addAndRecurse(owner *moduleAdapter, disabled bool) error {
 	moduleConfig := owner.Config()
 	if owner.projectMod {
 		if err := c.applyMounts(Import{}, owner); err != nil {
-			return err
+			return fmt.Errorf("failed to apply mounts for project module: %w", err)
 		}
 	}
 
@@ -618,7 +618,7 @@ func (c *collector) mountCommonJSConfig(owner *moduleAdapter, mounts []Mount) ([
 	// Mount the common JS config files.
 	fis, err := afero.ReadDir(c.fs, owner.Dir())
 	if err != nil {
-		return mounts, err
+		return mounts, fmt.Errorf("failed to read dir %q: %q", owner.Dir(), err)
 	}
 
 	for _, fi := range fis {