Do not remove unhandledRejection listeners as it breaks Serverless

[medikoo]

Removing unhandledRejection listener currently breaks exit code handling in Serverless 1.48.1+ -> serverless/serverless#6441, it technically turns off some important part of Serverless logic.

Serverless no longer forces process exit on unhandledRejection, so merging this in won't introduce a regression to #255 (which also should rather have been processed in context of serverless repo, not here)

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In future Serverless may force process exit on unhandledRejection but only if there were no listeners registered for it, which is on pair with Node.js deprecation warning:

[DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

[pmuens]

LGTM!

[dnalborczyk]

thank you @medikoo

Serverless no longer forces process exit on unhandledRejection

do you know approx. since which serverless version? offline currently has a peer-dependency on v1.39+ (because of websocket support, we have a check, but it's not enforced). just asking if we need to "up" the recommended peer dep version as well.

which also should rather have been processed in context of serverless repo, not here

probably so

[medikoo]

do you know approx. since what serverless version?

@dnalborczyk its's since v1.48.1