simplified error messages

internal/config/config.go

@@ -213,7 +213,7 @@ func (cfg *Config) loadProviders(providers *types.ProxyProviders) (outErr E.Nest
 		}
 		cfg.providers.Store(p.GetName(), p)
 		errs.Add(p.LoadRoutes().Subject(filename))
-		results.Addf("%d routes from %s", p.NumRoutes(), filename)
+		results.Addf("%d routes from %s", p.NumRoutes(), p.String())
 	}
 	for name, dockerHost := range providers.Docker {
 		p, err := proxy.NewDockerProvider(name, dockerHost)
@@ -223,7 +223,7 @@ func (cfg *Config) loadProviders(providers *types.ProxyProviders) (outErr E.Nest
 		}
 		cfg.providers.Store(p.GetName(), p)
 		errs.Add(p.LoadRoutes().Subject(p.GetName()))
-		results.Addf("%d routes from %s", p.NumRoutes(), name)
+		results.Addf("%d routes from %s", p.NumRoutes(), p.String())
 	}
 	logger.Info(results.Build())
 	return

internal/error/builder.go

@@ -1,8 +1,8 @@
 package error
 
 import (
+	"errors"
 	"fmt"
-	"strings"
 	"sync"
 )
 
@@ -23,12 +23,21 @@ func NewBuilder(format string, args ...any) Builder {
 	return Builder{&builder{message: format}}
 }
 
-// adding nil / nil is no-op,
-// you may safely pass expressions returning error to it.
-func (b Builder) Add(err NestedError) {
+// Add adds an error to the Builder.
+//
+// adding nil is no-op,
+//
+// flatten is a boolean flag to flatten the NestedError.
+func (b Builder) Add(err NestedError, flatten ...bool) {
 	if err != nil {
 		b.Lock()
-		b.errors = append(b.errors, err)
+		if len(flatten) > 0 && flatten[0] {
+			for _, e := range err.extras {
+				b.errors = append(b.errors, &e)
+			}
+		} else {
+			b.errors = append(b.errors, err)
+		}
 		b.Unlock()
 	}
 }
@@ -38,14 +47,26 @@ func (b Builder) AddE(err error) {
 }
 
 func (b Builder) Addf(format string, args ...any) {
-	b.Add(errorf(format, args...))
+	if len(args) > 0 {
+		b.Add(errorf(format, args...))
+	} else {
+		b.AddE(errors.New(format))
+	}
+}
+
+func (b Builder) AddRange(errs ...NestedError) {
+	b.Lock()
+	defer b.Unlock()
+	for _, err := range errs {
+		b.errors = append(b.errors, err)
+	}
 }
 
 func (b Builder) AddRangeE(errs ...error) {
 	b.Lock()
 	defer b.Unlock()
 	for _, err := range errs {
-		b.AddE(err)
+		b.errors = append(b.errors, From(err))
 	}
 }
 
@@ -59,8 +80,6 @@ func (b Builder) AddRangeE(errs ...error) {
 func (b Builder) Build() NestedError {
 	if len(b.errors) == 0 {
 		return nil
-	} else if len(b.errors) == 1 && !strings.ContainsRune(b.message, ' ') {
-		return b.errors[0].Subject(b.message)
 	}
 	return Join(b.message, b.errors...)
 }

internal/error/error.go

@@ -133,7 +133,11 @@ func (ne NestedError) With(s any) NestedError {
 	switch ss := s.(type) {
 	case nil:
 		return ne
-	case NestedError:
+	case *NestedErrorImpl:
+		if len(ss.extras) == 1 {
+			ne.extras = append(ne.extras, ss.extras[0])
+			return ne
+		}
 		return ne.withError(ss)
 	case error:
 		return ne.withError(From(ss))
@@ -248,10 +252,11 @@ func (ne NestedError) writeToSB(sb *strings.Builder, level int, prefix string) {
 		return
 	}
 
-	sb.WriteString(ne.err.Error())
 	if ne.subject != "" {
-		sb.WriteString(fmt.Sprintf(" for %q", ne.subject))
+		sb.WriteString(ne.subject)
+		sb.WriteRune(' ')
 	}
+	sb.WriteString(ne.err.Error())
 	if len(ne.extras) > 0 {
 		sb.WriteRune(':')
 		for _, extra := range ne.extras {

internal/route/provider/docker.go

@@ -33,7 +33,7 @@ func DockerProviderImpl(name, dockerHost string, explicitOnly bool) (ProviderImp
 }
 
 func (p *DockerProvider) String() string {
-	return "docker: " + p.name
+	return "docker@" + p.name
 }
 
 func (p *DockerProvider) NewWatcher() W.Watcher {

internal/route/provider/file.go

@@ -45,7 +45,7 @@ func (p FileProvider) String() string {
 func (p *FileProvider) LoadRoutesImpl() (routes R.Routes, res E.NestedError) {
 	routes = R.NewRoutes()
 
-	b := E.NewBuilder("file %q validation failure", p.fileName)
+	b := E.NewBuilder("validation failure")
 	defer b.To(&res)
 
 	entries := entry.NewProxyEntries()
@@ -61,7 +61,7 @@ func (p *FileProvider) LoadRoutesImpl() (routes R.Routes, res E.NestedError) {
 		return
 	}
 
-	b.Add(Validate(data))
+	b.Add(Validate(data), true)
 
 	return R.FromEntries(entries)
 }

internal/utils/serialization.go

@@ -48,7 +48,7 @@ func ValidateYaml(schema *jsonschema.Schema, data []byte) E.NestedError {
 
 	b := E.NewBuilder("yaml validation error")
 	for _, e := range valErr.Causes {
-		b.AddE(e)
+		b.Addf(e.Message)
 	}
 	return b.Build()
 }

internal/watcher/events/event_queue.go

@@ -62,7 +62,7 @@ func (e *EventQueue) Start(eventCh <-chan Event, errCh <-chan E.NestedError) {
 					go func() {
 						defer func() {
 							if err := recover(); err != nil {
-								e.onError(E.PanicRecv("onFlush: %s", err))
+								e.onError(E.PanicRecv("onFlush: %s", err).Subject(e.task.Parent().Name()))
 							}
 						}()
 						e.onFlush(flushTask, queue)