Use !! to convert to boolean

src/harness/fourslash.ts

@@ -911,7 +911,7 @@ namespace FourSlash {
 
             function rangeToReferenceEntry(r: Range) {
                 let { isWriteAccess, isDefinition } = (r.marker && r.marker.data) || { isWriteAccess: false, isDefinition: false };
-                isWriteAccess = isWriteAccess || false; isDefinition = isDefinition || false;
+                isWriteAccess = !!isWriteAccess; isDefinition = !!isDefinition;
                 return { fileName: r.fileName, textSpan: { start: r.start, length: r.end - r.start }, isWriteAccess, isDefinition }
             }
         }