fix(graphql): fix word spacing of error message when null

[DavidHavl]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe: Error message word spacing fix when null value

What is the current behavior?

Issue Number: N/A

What is the new behavior?

Does this PR introduce a breaking change?

• Yes
• No

Other information

[DavidHavl]

I know this is just a tiny issue/fix, but it was driving me crazy seeing it over and over in the console :) ... so I decided to fix it!

[jmcdo29]

I know this is just a tiny issue/fix, but it was driving me crazy seeing it over and over in the console :) ... so I decided to fix it!

Those are some of the best to get started. Looks good to me!

[kamilmysliwiec]

lgtm