Corrections to logged error messages. (#997)

cmd/clef/main.go

@@ -927,7 +927,7 @@ func GenDoc(ctx *cli.Context) {
 			if data, err := json.MarshalIndent(v, "", "  "); err == nil {
 				output = append(output, fmt.Sprintf("### %s\n\n%s\n\nExample:\n```json\n%s\n```", name, desc, data))
 			} else {
-				log.Error("Error generating output", err)
+				log.Error("Error generating output", "err", err)
 			}
 		}
 	)

cmd/puppeth/wizard_genesis.go

@@ -179,7 +179,7 @@ func (w *wizard) importGenesis() {
 	// Parse the genesis file and inject it successful
 	var genesis core.Genesis
 	if err := json.NewDecoder(reader).Decode(&genesis); err != nil {
-		log.Error("Invalid genesis spec: %v", err)
+		log.Error("Invalid genesis spec", "err", err)
 		return
 	}
 	log.Info("Imported genesis block")

raft/handler.go

@@ -870,7 +870,7 @@ func (pm *ProtocolManager) eventLoop() {
 					var block types.Block
 					err := rlp.DecodeBytes(entry.Data, &block)
 					if err != nil {
-						log.Error("error decoding block: ", err)
+						log.Error("error decoding block", "err", err)
 					}
 
 					if pm.blockchain.HasBlock(block.Hash(), block.NumberU64()) {