Simpler solution: getTypeFacts(neverType) should return TypeFacts.None

Author: ahejlsberg

src/compiler/checker.ts

@@ -19390,6 +19390,9 @@ namespace ts {
             if (flags & TypeFlags.NonPrimitive) {
                 return strictNullChecks ? TypeFacts.ObjectStrictFacts : TypeFacts.ObjectFacts;
             }
+            if (flags & TypeFlags.Never) {
+                return TypeFacts.None;
+            }
             if (flags & TypeFlags.Instantiable) {
                 return getTypeFacts(getBaseConstraintOfType(type) || unknownType);
             }
@@ -19626,7 +19629,7 @@ namespace ts {
                 const filtered = filter(types, f);
                 return filtered === types ? type : getUnionTypeFromSortedList(filtered, (<UnionType>type).objectFlags);
             }
-            return f(type) ? type : neverType;
+            return type.flags & TypeFlags.Never || f(type) ? type : neverType;
         }
 
         function countTypes(type: Type) {
@@ -28332,18 +28335,15 @@ namespace ts {
                 case SyntaxKind.InKeyword:
                     return checkInExpression(left, right, leftType, rightType);
                 case SyntaxKind.AmpersandAmpersandToken:
-                    return leftType === nonInferrableType || rightType === nonInferrableType ? nonInferrableType :
-                        getTypeFacts(leftType) & TypeFacts.Truthy ?
+                    return getTypeFacts(leftType) & TypeFacts.Truthy ?
                         getUnionType([extractDefinitelyFalsyTypes(strictNullChecks ? leftType : getBaseTypeOfLiteralType(rightType)), rightType]) :
                         leftType;
                 case SyntaxKind.BarBarToken:
-                    return leftType === nonInferrableType || rightType === nonInferrableType ? nonInferrableType :
-                        getTypeFacts(leftType) & TypeFacts.Falsy && leftType !== nonInferrableType ?
+                    return getTypeFacts(leftType) & TypeFacts.Falsy ?
                         getUnionType([removeDefinitelyFalsyTypes(leftType), rightType], UnionReduction.Subtype) :
                         leftType;
                 case SyntaxKind.QuestionQuestionToken:
-                    return leftType === nonInferrableType || rightType === nonInferrableType ? nonInferrableType :
-                        getTypeFacts(leftType) & TypeFacts.EQUndefinedOrNull && leftType !== nonInferrableType ?
+                    return getTypeFacts(leftType) & TypeFacts.EQUndefinedOrNull ?
                         getUnionType([getNonNullableType(leftType), rightType], UnionReduction.Subtype) :
                         leftType;
                 case SyntaxKind.EqualsToken: