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/manager/config/config.go

@@ -962,8 +962,7 @@ func (i *Instance) SetChecksumDefaultValues(defaultAlgorithm models.HashAlgorith
 	viper.SetDefault(CalculateMD5, usingMD5)
 }
 
-func (i *Instance) setDefaultValues() error {
-
+func (i *Instance) setDefaultValues(write bool) error {
 	// read data before write lock scope
 	defaultDatabaseFilePath := i.GetDefaultDatabaseFilePath()
 	defaultScrapersPath := i.GetDefaultScrapersPath()
@@ -989,11 +988,24 @@ func (i *Instance) setDefaultValues() error {
 	// Set default scrapers and plugins paths
 	viper.SetDefault(ScrapersPath, defaultScrapersPath)
 	viper.SetDefault(PluginsPath, defaultPluginsPath)
-	return viper.WriteConfig()
+	if write {
+		return viper.WriteConfig()
+	}
+
+	return nil
 }
 
 // SetInitialConfig fills in missing required config fields
 func (i *Instance) SetInitialConfig() error {
+	return i.setInitialConfig(true)
+}
+
+// SetInitialMemoryConfig fills in missing required config fields without writing the configuration
+func (i *Instance) SetInitialMemoryConfig() error {
+	return i.setInitialConfig(false)
+}
+
+func (i *Instance) setInitialConfig(write bool) error {
 	// generate some api keys
 	const apiKeyLength = 32
 
@@ -1007,7 +1019,7 @@ func (i *Instance) SetInitialConfig() error {
 		i.Set(SessionStoreKey, sessionStoreKey)
 	}
 
-	return i.setDefaultValues()
+	return i.setDefaultValues(write)
 }
 
 func (i *Instance) FinalizeSetup() {