Bug: TypeError: Cannot read property 'match' of null

[skaematik]

Sometimes I would get the error message TypeError: Cannot read property 'match' of null. e.g.:

All changes pushed ✅

This will create (or update) PRs for the following branches:
  -> annie/a (x1)
  -> annie/b (x2)
  -> annie/c (x3)

Shall we do this? [y/n]  y

Checking if PR for branch annie/a already exists... yep
Checking if PR for branch annie/b already exists... yep
Checking if PR for branch annie/c already exists... yep
Updating PR for branch annie/a...✅
❌  An error occured. Was there a conflict perhaps?
error TypeError: Cannot read property 'match' of null
    at upsertNavigationInBody (/usr/local/lib/node_modules/git-pr-train/github.js:70:12)
    at allBranches.reduce (/usr/local/lib/node_modules/git-pr-train/github.js:200:21)
    at process._tickCallback (internal/process/next_tick.js:68:7)

I believe the issue is that memo.body can be null.

pr-train/github.js

Line 176 in 8fdaa9a

body: prResponse.body,