TypeError: Cannot read property 'type' of undefined

[ikatyang]

version: 1.0.0-beta.5

input:

abc: 123
def

output:

TypeError: Cannot read property 'type' of undefined
    at YAMLMap.resolveBlockMapItems (./node_modules/yaml/dist/schema/Map.js:152:34)
    at YAMLMap.parse (./node_modules/yaml/dist/schema/Map.js:71:14)
    at Object.resolve (./node_modules/yaml/dist/schema/failsafe.js:22:34)
    at Tags.resolveNode (./node_modules/yaml/dist/Tags.js:129:29)
    at Tags.resolveNodeWithFallback (./node_modules/yaml/dist/Tags.js:153:22)
    at Document.resolveNode (./node_modules/yaml/dist/Document.js:302:22)
    at ./node_modules/yaml/dist/Document.js:116:35
    at Array.forEach (<anonymous>)
    at Document.parse (./node_modules/yaml/dist/Document.js:114:16)

expected:

A syntax error.