Fix concurrency crash. Closes #1067 An error occurred

core/data/cache.go

@@ -1,9 +1,17 @@
 package data
 
-import "errors"
+import (
+	"errors"
+	"sync"
+)
+
+var _cacheLock = sync.Mutex{}
 
 // GetCachedValue will return a value for key from the cache.
 func (ds *Datastore) GetCachedValue(key string) ([]byte, error) {
+	_cacheLock.Lock()
+	defer _cacheLock.Unlock()
+
 	// Check for a cached value
 	if val, ok := ds.cache[key]; ok {
 		return val, nil
@@ -14,5 +22,8 @@ func (ds *Datastore) GetCachedValue(key string) ([]byte, error) {
 
 // SetCachedValue will set a value for key in the cache.
 func (ds *Datastore) SetCachedValue(key string, b []byte) {
+	_cacheLock.Lock()
+	defer _cacheLock.Unlock()
+
 	ds.cache[key] = b
 }