Add error checking for missing data parameter

[dpilafian]

If the data field is missing when cloning a template, the current error message is very confusing. There should be an clear, explicit error message when data is undefined.

const data = undefined;
dna.clone('book', data);  //should immediately throw an error

[dpilafian]

Add a check just before the "Container missing for nested template" check at:
https://github.com/dnajs/dna.js/blob/master/dna.js#L43

with a message something like:

dna.core.berserk('Required data field missing in call to dna.clone', name);

[giteshk11]

Hi @dpilafian , I would like to work on this issue

[dpilafian]

@giteshk11 Thanks for completing issue #78 👍.

If you're looking to make additional open source contributions, here are some projects with good "first" issues:

• https://github.com/center-key/pretty-print-json
• https://github.com/center-key/fetch-json
• https://github.com/center-key/clabe-validator