boom.unathorized adds extra space to string value scheme in WWW-Authenticate header

[seanstern]

Support plan

• which support plan is this issue covered by? (e.g. Community, Core, Plus, or Enterprise): Community
• is this issue currently blocking your project? (yes/no): no
• is this issue affecting a production system? (yes/no): no

Context

• node version: 10.17.0
• module version with issue: 8.0.1
• last module version without issue: Unknown
• environment (e.g. node, browser, native): Node
• used with (e.g. hapi application, another framework, standalone, ...): Standalone
• any other relevant information: -- The issue seems to be generated by this line of code in the @hapi/boom library. -- One can work around the issue by passing an array value with a single string as the scheme argument of the unauthorized function. For example boom.unauthorized(null, ['Bearer']) produces the correct value.

What are you trying to achieve or the steps to reproduce?

I want to produce an unauthorized error where the WWW-Authenticate header's value is scheme that is specified at runtime. In the example below the string value 'Bearer'. Note that this string value has no spaces before or after it.

const boom = require('@hapi/boom');
const authErr = boom.unauthorized(null, 'Bearer');
console.log(authErr);

What was the result you got?

The error object's WWW-Authenticate property's value has an extra space at the end ('Bearer ').

{ Error: Unauthorized
    at repl:1:9
    // Stack trace redacted for brevity
  data: null,
  isBoom: true,
  isServer: false,
  output:
   { statusCode: 401,
     payload:
      { statusCode: 401,
        error: 'Unauthorized',
        message: 'Unauthorized' },
     headers: { 'WWW-Authenticate': 'Bearer ' } },  // Note the space at the end
  message: 'Unauthorized' }

What result did you expect?

The error object's WWW-Authenticate property's value should not have an extra space at the end ('Bearer').

{ Error: Unauthorized
    at repl:1:9
    // Stack trace redacted for brevity
  data: null,
  isBoom: true,
  isServer: false,
  output:
   { statusCode: 401,
     payload:
      { statusCode: 401,
        error: 'Unauthorized',
        message: 'Unauthorized' },
     headers: { 'WWW-Authenticate': 'Bearer' } },  // Note there is NO space at the end
  message: 'Unauthorized' }