Replace deprecated util._extend API with Object.assign()

[terrencekhng]

What's going wrong?

Reference: https://nodejs.org/api/util.html#util_extendtarget-source
The util._extend() method was never intended to be used outside of internal Node.js modules. There are some modules in pm2 still using this method, and it is hereafter suggested to be replaced.

How could we reproduce this issue?

N/A

Supporting information

N/A

$ pm2 report

[enkr1]

any update on this?

[eliliam]

@Unitech could we get an update since it's been three years since the issue was created? I'm also seeing this warning happening more frequently now.

[NicmeisteR]

Yeah having this error pop up consistently is a bit of a pain , also hoping for a fix soon.

[egoroof]

Should be fixed in keymetrics/pm2-io-apm#303

[egoroof]

should be fixed in v5.4.2