Remove unreachable code to fix go vet (#249)

decode.go

@@ -120,7 +120,6 @@ func (p *parser) parse() *node {
 	default:
 		panic("attempted to parse unknown event: " + strconv.Itoa(int(p.event.typ)))
 	}
-	panic("unreachable")
 }
 
 func (p *parser) node(kind int) *node {

emitterc.go

@@ -666,7 +666,6 @@ func yaml_emitter_emit_node(emitter *yaml_emitter_t, event *yaml_event_t,
 		return yaml_emitter_set_emitter_error(emitter,
 			"expected SCALAR, SEQUENCE-START, MAPPING-START, or ALIAS")
 	}
-	return false
 }
 
 // Expect ALIAS.

parserc.go

@@ -166,7 +166,6 @@ func yaml_parser_state_machine(parser *yaml_parser_t, event *yaml_event_t) bool
 	default:
 		panic("invalid parser state")
 	}
-	return false
 }
 
 // Parse the production: