Add error handling for configuration node

[kazuhitoyokoi]

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Proposed changes

I added the error handling for the configuration node in swagger node template.

Checklist

• I have read the contribution guidelines
• For non-bugfix PRs, I have discussed this change on the mailing list/slack team.
• I have run grunt to verify the unit tests pass
• I have added suitable unit tests to cover the new/changed functionality

[coveralls]

Coverage increased (+0.9%) to 68.099% when pulling 14a9451 on kazuhitoyokoi:master-fixconfignodeerror into aabec5a on node-red:master.