fixes

Author: xtqqczze

src/libraries/System.Private.CoreLib/src/System/Runtime/CompilerServices/GenericCache.cs

@@ -141,7 +141,6 @@ private static ref Entry Element(Entry[] table, int index)
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         internal bool TryGet(TKey key, out TValue? value)
         {
-            // table is always initialized and is not null.
             Entry[] table = _table;
             int hash = key.GetHashCode();
             int index = HashToBucket(table, hash);

src/tools/illink/src/ILLink.Shared/DataFlow/ForwardDataFlowAnalysis.cs

@@ -408,7 +408,7 @@ public void Fixpoint(TControlFlowGraph cfg, TTransfer transfer)
                             // Filters can't contain try/catch/filters.
                             Debug.Assert(enclosingTryOrCatch.Kind != RegionKind.Filter);
                             Box<TValue> tryOrCatchExceptionState = cfgState.GetExceptionState(enclosingTryOrCatch);
-                            tryOrCatchExceptionState.Value = lattice.Meet(tryOrCatchExceptionState.Value, exceptionState.Value);
+                            tryOrCatchExceptionState.Value = lattice.Meet(tryOrCatchExceptionState.Value, exceptionState!.Value);
                             tryOrCatchOrFilterRegion = enclosingTryOrCatch;
                         }
                     }

src/tools/illink/src/ILLink.Shared/MessageFormat.cs

@@ -11,7 +11,7 @@ internal static class MessageFormat
         public static string FormatRequiresAttributeMessageArg(string? message)
         {
             if (!string.IsNullOrEmpty(message))
-                return $" {message}{(message.TrimEnd().EndsWith(".") ? "" : ".")}";
+                return $" {message}{(message!.TrimEnd().EndsWith(".") ? "" : ".")}";
 
             return string.Empty;
         }