Errcheck phase 1 (#1715)

* Avoid redundant logging in migrations

Return the error and let the caller handle the logging of the error if
needed.

While here, defer m.Close() to the function boundary.

* Treat errors as values

Use %v rather than %s and pass the errors directly.

* Generate a wrapped error on stat-failure

* Log 3 unchecked errors

Rather than ignore errors, log them at
the WARNING log level.

The server has been functioning without these, so assume they are not at
the ERROR level.

* Propagate errors upward

Failure in path generation was ignored. Propagate the errors upward the
call stack, so it can be handled at the level of orchestration.

* Warn on errors

Log errors rather than quenching them.

Errors are logged at the Warn-level for now.

* Check error when creating test databases

Use the builtin log package and stop the program fatally on error.

* Add warnings to uncheck task errors

Focus on the task system in a single commit, logging unchecked
errors as warnings.

* Warn-on-error in API routes

Look through the API routes, and make sure errors are being logged if
they occur. Prefer the Warn-log-level because none of these has proven
to be fatal in the system up until now.

* Propagate error when adding Util API

* Propagate error on adding util API

* Return unhandled error

* JS log API: propagate and log errors

* JS Plugins: log GQL addition failures.

* Warn on failure to write to stdin

* Warn on failure to stop task

* Wrap viper.BindEnv

The current viper code only errors if no name is provided, so it should
never fail. Rewrite the code flow to factor through a panic-function.

This removes error warnings from this part of the code.

* Log errors in concurrency test

If we can't initialize the configuration, treat the test as a failure.

* Warn on errors in configuration code

* Plug an unchecked error in gallery zip walking

* Warn on screenshot serving failure

* Warn on encoder screenshot failure

* Warn on errors in path-handling code

* Undo the errcheck on configurations for now.

* Use one-line initializers where applicable

rather than using

  err := f()
  if err!= nil { ..

prefer the shorter

  if err := f(); err != nil { ..

If f() isn't too long of a name, or wraps a function with a body.

pkg/manager/task_scan.go

@@ -87,7 +87,9 @@ func (j *ScanJob) Execute(ctx context.Context, progress *job.Progress) {
 				galleries = append(galleries, path)
 			}
 
-			instance.Paths.Generated.EnsureTmpDir()
+			if err := instance.Paths.Generated.EnsureTmpDir(); err != nil {
+				logger.Warnf("couldn't create temporary directory: %v", err)
+			}
 
 			wg.Add()
 			task := ScanTask{
@@ -126,7 +128,11 @@ func (j *ScanJob) Execute(ctx context.Context, progress *job.Progress) {
 	}
 
 	wg.Wait()
-	instance.Paths.Generated.EmptyTmpDir()
+
+	if err := instance.Paths.Generated.EmptyTmpDir(); err != nil {
+		logger.Warnf("couldn't empty temporary directory: %v", err)
+	}
+
 	elapsed := time.Since(start)
 	logger.Info(fmt.Sprintf("Scan finished (%s)", elapsed))
 
@@ -753,7 +759,7 @@ func (t *ScanTask) scanScene() *models.Scene {
 
 	// check for scene by checksum and oshash - MD5 should be
 	// redundant, but check both
-	t.TxnManager.WithReadTxn(context.TODO(), func(r models.ReaderRepository) error {
+	txnErr := t.TxnManager.WithReadTxn(context.TODO(), func(r models.ReaderRepository) error {
 		qb := r.Scene()
 		if checksum != "" {
 			s, _ = qb.FindByChecksum(checksum)
@@ -765,6 +771,9 @@ func (t *ScanTask) scanScene() *models.Scene {
 
 		return nil
 	})
+	if txnErr != nil {
+		logger.Warnf("error in read transaction: %v", txnErr)
+	}
 
 	sceneHash := oshash
 
@@ -1320,7 +1329,7 @@ func (t *ScanTask) doesPathExist() bool {
 	gExt := config.GetGalleryExtensions()
 
 	ret := false
-	t.TxnManager.WithReadTxn(context.TODO(), func(r models.ReaderRepository) error {
+	txnErr := t.TxnManager.WithReadTxn(context.TODO(), func(r models.ReaderRepository) error {
 		if matchExtension(t.FilePath, gExt) {
 			gallery, _ := r.Gallery().FindByPath(t.FilePath)
 			if gallery != nil {
@@ -1340,6 +1349,9 @@ func (t *ScanTask) doesPathExist() bool {
 
 		return nil
 	})
+	if txnErr != nil {
+		logger.Warnf("error while executing read transaction: %v", txnErr)
+	}
 
 	return ret
 }