check vectors *early*, because: pain, so much pain

src/StackExchange.Redis/ConnectionMultiplexer.cs

@@ -965,8 +965,33 @@ internal ServerEndPoint GetServerEndPoint(EndPoint endpoint, TextWriter log = nu
         }
 
         internal readonly CommandMap CommandMap;
+
+        [MethodImpl(MethodImplOptions.NoInlining)]
+        private static void CheckNumericsVectors()
+        {
+            try
+            {
+                DoNothingWith(System.Numerics.Vector.IsHardwareAccelerated, System.Numerics.Vector<int>.Count);
+            }
+            catch (Exception ex)
+            {
+                throw new InvalidOperationException(
+                    "It looks like there's a problem resolving System.Numerics.Vectors.dll; "
+                    + "this is a well-known pain point between .NET Framework and .NET Core - "
+                    + "try adding an explicit package reference to System.Numerics.Vectors; "
+                    + "and if you're wondering 'why do you need that?' - we actually don't: "
+                    + "it is a down-stream dependency that we don't need directly, but which "
+                    + "keeps causing pain.", ex);
+            }
+        }
+        [MethodImpl(MethodImplOptions.NoInlining)]
+#pragma warning disable RCS1163 // Unused parameter.
+        private static void DoNothingWith(bool b, int i) { }
+#pragma warning restore RCS1163 // Unused parameter.
         private ConnectionMultiplexer(ConfigurationOptions configuration)
         {
+            CheckNumericsVectors();
+
             IncludeDetailInExceptions = true;
             IncludePerformanceCountersInExceptions = false;