TypeError: Cannot read property 'startsWith' of undefined

[joojis]

TypeError: Cannot read property 'startsWith' of undefined
    at Function.convertSignatureStringToRsv (/home/gnu/my-project/node_modules/codechain-sdk/lib/core/SignedParcel.js:145:23)
    at new SignedParcel (/home/gnu/my-project/node_modules/codechain-sdk/lib/core/SignedParcel.js:35:42)
    at ChainRpc.<anonymous> (/home/gnu/my-project/node_modules/codechain-sdk/lib/rpc/chain.js:68:42)
    at Generator.next (<anonymous>)
    at fulfilled (/home/gnu/my-project/node_modules/codechain-sdk/lib/rpc/chain.js:4:58)
    at <anonymous>
    at process._tickCallback (internal/process/next_tick.js:188:7)

To print a proper error message, The sig field must be validated in SignedParcel constructor.

[joojis]

The error occurs when the signature is undefined.
The signature was able to become undefined when the sign() RPC call returned undefined(because of the proxy). It was fixed after the patch validating RPC responses. 232df26