Prevent NullReferenceException found in telemetry (#2644)

We found a NRE in Power Apps telemetry that was happening in the Intellisense code on Power Fx. We don't know exactly the cause, but this change adds a defense-in-depth that will help preventing that.

src/libraries/Microsoft.PowerFx.Core/Texl/Intellisense/Intellisense.cs

@@ -187,13 +187,14 @@ protected static void TypeMatchPriority(DType type, IList<IntellisenseSuggestion
 
             foreach (var suggestion in suggestions)
             {
-                if (!suggestion.Type.IsUnknown &&
+                var suggestionType = suggestion.Type;
+                if (!suggestionType.IsUnknown &&
 
                     // Most type acceptance is straightforward
-                    (type.Accepts(suggestion.Type, exact: true, useLegacyDateTimeAccepts: false, usePowerFxV1CompatibilityRules: usePowerFxV1CompatibilityRules) ||
+                    (type.Accepts(suggestionType, exact: true, useLegacyDateTimeAccepts: false, usePowerFxV1CompatibilityRules: usePowerFxV1CompatibilityRules) ||
 
                     // Option Set expected types should also include the option set base as a reccomendation.
-                    (suggestion.Type.IsOptionSet && type.Accepts(DType.CreateOptionSetValueType(suggestion.Type.OptionSetInfo), exact: true, useLegacyDateTimeAccepts: false, usePowerFxV1CompatibilityRules: usePowerFxV1CompatibilityRules))))
+                    (suggestionType.IsOptionSet && suggestionType.OptionSetInfo != null && type.Accepts(DType.CreateOptionSetValueType(suggestionType.OptionSetInfo), exact: true, useLegacyDateTimeAccepts: false, usePowerFxV1CompatibilityRules: usePowerFxV1CompatibilityRules))))
                 {
                     suggestion.SortPriority++;
                 }