fix(typescript): handle global namespace without modifiers (#1646)

src/printer.js

@@ -2414,7 +2414,8 @@ function genericPrintNoParens(path, options, print, args) {
         // declare global { ... }
         const isGlobalDeclaration = n.name.type === "Identifier" &&
           n.name.name === "global" &&
-            n.modifiers.some(modifier => modifier.type === "TSDeclareKeyword");
+            n.modifiers &&
+              n.modifiers.some(modifier => modifier.type === "TSDeclareKeyword");
 
         if (!isGlobalDeclaration) {
           parts.push(isExternalModule ? "module " : "namespace ");

tests/typescript/compiler/__snapshots__/jsfmt.spec.js.snap

@@ -238,6 +238,42 @@ interface C {
 
 `;
 
+exports[`globalIsContextualKeyword.ts 1`] = `
+function a() {
+    let global = 1;
+}
+function b() {
+    class global {}
+}
+
+namespace global {
+}
+
+function foo(global: number) {
+}
+
+let obj = {
+    global: "123"
+}~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+function a() {
+  let global = 1;
+}
+function b() {
+  class global {}
+}
+
+namespace global {
+
+}
+
+function foo(global: number) {}
+
+let obj = {
+  global: "123"
+};
+
+`;
+
 exports[`indexSignatureWithInitializer.ts 1`] = `
 // These used to be indexers, now they are computed properties
 interface I {

tests/typescript/compiler/globalIsContextualKeyword.ts

@@ -0,0 +1,16 @@
+function a() {
+    let global = 1;
+}
+function b() {
+    class global {}
+}
+
+namespace global {
+}
+
+function foo(global: number) {
+}
+
+let obj = {
+    global: "123"
+}