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Co-authored-by: Andrei Litvin <[email protected]>

src/lib/address_resolve/AddressResolve_DefaultImpl.cpp

@@ -248,6 +248,8 @@ CHIP_ERROR Resolver::Init(System::Layer * systemLayer)
 
 void Resolver::Shutdown()
 {
+    // mSystemLayer is set in ::Init, so if it's null that means the resolver
+    // has not been initialized or has already been shut down.
     VerifyOrReturn(mSystemLayer != nullptr);
 
     while (mActiveLookups.begin() != mActiveLookups.end())