The `speculations` object may be null at the call to `Collection.add`[1].

[1] http://hg.openjdk.java.net/jdk10/hs/hotspot/file/49b13c8cb641/src/jdk.vm.ci/share/classes/jdk.vm.ci.hotspot/src/jdk/vm/ci/hotspot/HotSpotSpeculationLog.java#l80