Crash when instrumenting request with null headers

[OuranosSkia]

Description

When instrumenting some older libraries, it appears that newrelic does not properly handle things and causes a crash. In this case, the instrumentation is happening where opts.headers is null instead of an object or undefined. null does not get handled properly by defaulting and throws an error when it checks for the existence of specific headers.

Expected Behavior

The system should handle opts.headers being null the same as undefined and thus properly default it to an empty object for handling.
NOTE: # ( Tell us what you expected to happen. )

Troubleshooting or NR Diag results

Steps to Reproduce

It's difficult to reproduce as the situation is very specifically dependent on both the system we use and the way we use it (which I do not feel comfortable sharing here).
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TIP: # ( Link a sample application that demonstrates the issue. )

Your Environment

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Additional context

[workato-integration]

https://new-relic.atlassian.net/browse/NR-200385