Update the submodule "core" by merging the pull request

jonghenhan · jonghenhan · commit 74b683044d1f · 2021-02-26T10:48:47.000+09:00
from jonghenhan/master
Fix crash issue in DiscoveryManager.m
diff --git a/core b/core
@@ -1 +1 @@
-Subproject commit b66b90474a86bae57fe8428c764091674cac554a
+Subproject commit 9fe784fe0b7b95de383b83280b2f3df7921f584b
