Lint checks phase 2 (#1747)

* 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.

* Log errors in concurrency test

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

* Undo the errcheck on configurations for now.

* Handle unchecked errors in pkg/manager

* Resolve unchecked errors

* Handle DLNA/DMS unchecked errors

* Handle error checking in concurrency test

Generalize config initialization, so we can initialize a configuration
without writing it to disk.

Use this in the test case, since otherwise the test fails to write.

* Handle the remaining unchecked errors

* Heed gosimple in update test

* Use one-line if-initializer statements

While here, fix a wrong variable capture error.

* testing.T doesn't support %w

use %v instead which is supported.

* Remove unused query builder functions

The Int/String criterion handler functions are now generalized.

Thus, there's no need to keep these functions around anymore.

* Mark filterBuilder.addRecursiveWith nolint

The function is useful in the future and no other refactors are looking
nice.

Keep the function around, but tell the linter to ignore it.

* Remove utils.Btoi

There are no users of this utility function

* Return error on scan failure

If we fail to scan the row when looking for the
unique checksum index, then report the error upwards.

* Fix comments on exported functions

* Fix typos

* Fix startup error

pkg/api/resolver_mutation_metadata.go

@@ -2,6 +2,7 @@ package api
 
 import (
 	"context"
+	"fmt"
 	"io/ioutil"
 	"path/filepath"
 	"strconv"
@@ -105,7 +106,9 @@ func (r *mutationResolver) BackupDatabase(ctx context.Context, input models.Back
 	mgr := manager.GetInstance()
 	var backupPath string
 	if download {
-		utils.EnsureDir(mgr.Paths.Generated.Downloads)
+		if err := utils.EnsureDir(mgr.Paths.Generated.Downloads); err != nil {
+			return nil, fmt.Errorf("could not create backup directory %v: %w", mgr.Paths.Generated.Downloads, err)
+		}
 		f, err := ioutil.TempFile(mgr.Paths.Generated.Downloads, "backup*.sqlite")
 		if err != nil {
 			return nil, err