[Erlang server] handle broken JSON

[velzevur]

PR checklist

• Read the contribution guidelines.
• Ran the shell script under ./bin/ to update Petstore sample so that CIs can verify the change. (For instance, only need to run ./bin/{LANG}-petstore.sh and ./bin/security/{LANG}-petstore.sh if updating the {LANG} (e.g. php, ruby, python, etc) code generator or {LANG} client's mustache templates). Windows batch files can be found in .\bin\windows\.
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Description of the PR

Fixes #7128
If the decoding of the JSON fails - the error is caught and propagated

[wing328]

cc @galaxie @tsloughter

[tsloughter]

@velzevur why does this change the samples/server/petstore/erlang-server/priv/swagger.json file?

And this is good, but ultimately we need to move the json decoding out of the api.mustache, partly since it isn't always going to even be json but have to be based on the content type.

So what I'd like to see is a library that can be used to handle all that and the api.mustache functions simply pass everything it builds up and currently passes to hackney to pass to it (which ultimately will also use hackney).

Just letting you know in case you or someone you know looks to work on this more :) Thanks!

[velzevur]

@tsloughter I was wondering the same, I guess the samples/server/petstore/erlang-server/priv/swagger.json wasn't up to date for some reason.
Same holds true for the VERSION, too