Check following extraneous data (#359)

[zensh]

Signed-off-by: Yan Qing admin@zensh.com

Description

PR Was Proposed and Welcomed in Currently Open Issue

• This PR was proposed and welcomed by maintainer(s) in issue bug: Unmarshal and Valid should check following extraneous data #359
• Closes or Updates Issue bug: Unmarshal and Valid should check following extraneous data #359

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[fxamacker]

@zensh Thanks for opening this PR and issue #359. Sorry about the delay.

As mentioned just now in issue comment, after spending more time looking into this, I think this should be handled without changing API signature and by making the default behavior match how it's handled in encoding/json.

Also, I think we should define and return ExtraneousDataError instead of SyntaxError.

Please let me know if you prefer to update this PR or if I should open a new PR. Thanks!

[zensh]

Looking forward to your PR