Apply suggestions from code review

Co-authored-by: Nathan Shively-Sanders <[email protected]>

Author: uhyo

src/compiler/parser.ts

@@ -3579,20 +3579,15 @@ namespace ts {
                 const type = parseFunctionOrConstructorType();
                 let diagnostic: DiagnosticMessage;
                 if (isFunctionTypeNode(type)) {
-                    if (isInUnionType) {
-                        diagnostic = Diagnostics.Function_type_notation_must_be_parenthesized_when_used_in_a_union_type;
-                    }
-                    else {
-                        diagnostic = Diagnostics.Function_type_notation_must_be_parenthesized_when_used_in_an_intersection_type;
-                    }
+                    diagnostic = isInUnionType
+                        ? Diagnostics.Function_type_notation_must_be_parenthesized_when_used_in_a_union_type;
+                        : Diagnostics.Function_type_notation_must_be_parenthesized_when_used_in_an_intersection_type;
                 }
                 else {
-                    if (isInUnionType) {
-                        diagnostic = Diagnostics.Constructor_type_notation_must_be_parenthesized_when_used_in_a_union_type;
-                    }
-                    else {
-                        diagnostic = Diagnostics.Constructor_type_notation_must_be_parenthesized_when_used_in_an_intersection_type;
-                    }
+                    diagnostic = isInUnionType ?
+                        ? Diagnostics.Constructor_type_notation_must_be_parenthesized_when_used_in_a_union_type
+                        : Diagnostics.Constructor_type_notation_must_be_parenthesized_when_used_in_an_intersection_type;
+
                 }
                 parseErrorAtRange(type, diagnostic);
                 return type;
@@ -3607,9 +3602,8 @@ namespace ts {
         ): TypeNode {
             const pos = getNodePos();
             const hasLeadingOperator = parseOptional(operator);
-            let type = hasLeadingOperator ?
-                parseFunctionOrConstructorTypeToError(operator === SyntaxKind.BarToken) || parseConstituentType() :
-                parseConstituentType();
+            let type = hasLeadingOperator && parseFunctionOrConstructorTypeToError(operator === SyntaxKind.BarToken) 
+                || parseConstituentType();
             if (token() === operator || hasLeadingOperator) {
                 const types = [type];
                 while (parseOptional(operator)) {