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/ffmpeg/encoder.go

@@ -63,7 +63,9 @@ func KillRunningEncoders(path string) {
 	for _, process := range processes {
 		// assume it worked, don't check for error
 		logger.Infof("Killing encoder process for file: %s", path)
-		process.Kill()
+		if err := process.Kill(); err != nil {
+			logger.Warnf("failed to kill process %v: %v", process.Pid, err)
+		}
 
 		// wait for the process to die before returning
 		// don't wait more than a few seconds