Fix: Convert type guards (fixes #282)

lib/ast-node-types.js

@@ -122,6 +122,7 @@ module.exports = {
     TSQuestionToken: "TSQuestionToken",
     TSStringKeyword: "TSStringKeyword",
     TSTypeLiteral: "TSTypeLiteral",
+    TSTypePredicate: "TSTypePredicate",
     TSTypeReference: "TSTypeReference",
     TSUnionType: "TSUnionType",
     TSVoidKeyword: "TSVoidKeyword",

lib/convert.js

@@ -1724,6 +1724,14 @@ module.exports = function convert(config) {
 
         }
 
+        case SyntaxKind.FirstTypeNode:
+            Object.assign(result, {
+                type: AST_NODE_TYPES.TSTypePredicate,
+                parameterName: convertChild(node.parameterName),
+                typeAnnotation: convertTypeAnnotation(node.type)
+            });
+            break;
+
         default:
             deeplyCopy();
     }