fix int bitlength issue in TestChainConfig_LoadForks

Author: gballet

beacon/params/config.go

@@ -108,6 +108,8 @@ func (c *ChainConfig) LoadForks(file []byte) error {
 			switch version := value.(type) {
 			case int:
 				versions[name] = new(big.Int).SetUint64(uint64(version)).FillBytes(make([]byte, 4))
+			case int64:
+				versions[name] = new(big.Int).SetUint64(uint64(version)).FillBytes(make([]byte, 4))
 			case uint64:
 				versions[name] = new(big.Int).SetUint64(version).FillBytes(make([]byte, 4))
 			case string:
@@ -125,6 +127,8 @@ func (c *ChainConfig) LoadForks(file []byte) error {
 			switch epoch := value.(type) {
 			case int:
 				epochs[name] = uint64(epoch)
+			case int64:
+				epochs[name] = uint64(epoch)
 			case uint64:
 				epochs[name] = epoch
 			case string: