CI: Fix golangci-lint linter issues, add prealloc linter and bump version depends for Go 1.18 (#915)

* Bump CI versions

* Specifically set go version as 1.17.x bumps it to 1.18

* Another

* Adjust AppVeyor

* Part 1 of linter issues

* Part 2

* Fix various linters and improvements

* Part 3

* Finishing touches

* Tests and EqualFold

* Fix nitterinos plus bonus requester jobs bump for exchanges with large number of tests

* Fix nitterinos and bump golangci-lint timeout for AppVeyor

* Address nits, ensure all books are returned on err due to syncer regression

* Fix the wiggins

* Fix duplication

* Fix nitterinos

dispatch/dispatch.go

@@ -285,11 +285,11 @@ func (d *Dispatcher) subscribe(id uuid.UUID) (chan interface{}, error) {
 
 	// Read lock to read route list
 	d.rMtx.RLock()
-	_, ok := d.routes[id]
-	d.rMtx.RUnlock()
-	if !ok {
+	if _, ok := d.routes[id]; !ok {
+		d.rMtx.RUnlock()
 		return nil, errors.New("dispatcher uuid not found in route list")
 	}
+	d.rMtx.RUnlock()
 
 	// Get an unused channel from the channel pool
 	unusedChan, ok := d.outbound.Get().(chan interface{})
@@ -314,11 +314,11 @@ func (d *Dispatcher) unsubscribe(id uuid.UUID, usedChan chan interface{}) error
 
 	// Read lock to read route list
 	d.rMtx.RLock()
-	_, ok := d.routes[id]
-	d.rMtx.RUnlock()
-	if !ok {
+	if _, ok := d.routes[id]; !ok {
+		d.rMtx.RUnlock()
 		return errors.New("dispatcher uuid does not reference any channels")
 	}
+	d.rMtx.RUnlock()
 
 	// Lock for write to delete references
 	d.rMtx.Lock()

dispatch/dispatch_types.go

@@ -71,7 +71,6 @@ type job struct {
 type Mux struct {
 	// Reference to the main running dispatch service
 	d *Dispatcher
-	sync.RWMutex
 }
 
 // Pipe defines an outbound object to the desired routine