nil value for Rollbar::Util.deep_merge first argument

[fabn]

With release 2.7.0 I got the actual error message for the issued described in #354 that is

Failsafe from rollbar-gem. NoMethodError: "undefined method `[]' for nil:NilClass" in lib/rollbar/util.rb:70:in `block in deep_merge': build_payload in exception_data

So instead of the patch discussed here the right fix should check if hash1 is nil.

However I don't know how to handle that case because I don't know the semantic of that method.

Looking at the code a simple hash1 ||= {} before the each_key loop may fix the issue but I don't know what consequences may have on the other code, so I won't submit a PR for that.

[jondeandres]

Thanks for this investigation @fabn. We'll try to reproduce this and fix this soon.

Your solution may work, but we will need to check exactly what is happening.

Thanks for this!