call setGlobalLabel causes exception when apm is not activated

[binsee]

Describe the bug

When starting with { active: false}, calling setGlobalLabel triggers an exception: TypeError: Cannot read properties of null (reading 'config')

To Reproduce

Steps to reproduce the behavior:

1. Use this config '{ active: false}'
2. Then call 'setGlobalLabel'
3. See error:

/Users/binsee/CodeWork/test/node_modules/elastic-apm-node/lib/agent.js:368
   this._apmClient.config({
                   ^
TypeError: Cannot read properties of null (reading 'config')
     at Agent.setGlobalLabel (/Users/binsee/CodeWork/test/node_modules/elastic-apm-node/lib/agent.js:368:19)
     at Object.<anonymous> (/Users/binsee/CodeWork/test/src/1.ts:4:5)

Expected behavior

Regardless of whether it is active or not, no error should be reported

Environment (please complete the following information)

• OS: MacOS
• Node.js version: 16.19.0
• APM Server version: ``
• Agent version: 3.47.0

How are you starting the agent? (please tick one of the boxes)

• Calling agent.start() directly (e.g. require('elastic-apm-node').start(...))
• Requiring elastic-apm-node/start from within the source code
• Starting node with -r elastic-apm-node/start

Additional context

Agent config options:

Click to expand

{ active: false }

package.json dependencies:

Click to expand

   "elastic-apm-node": "^3.47.0",

Test code:

Click to expand

import apm from 'elastic-apm-node'

apm. start({ active: false })
apm.setGlobalLabel('token', 'test-01')

setTimeout(() => {
   console. log('hello')
}, 5000)