Don't insert a cursor placeholder for a value-less path (#2136)

* Test that no cursor placeholder is inserted for a value-less path

This was taken from https://github.com/prettier/prettier/issues/2131

* Don't insert a cursor placeholder for a value-less path

This fixes https://github.com/prettier/prettier/issues/2131

src/comments.js

@@ -934,7 +934,7 @@ function printDanglingComments(path, options, sameIndent) {
 }
 
 function prependCursorPlaceholder(path, options, printed) {
-  if (path.getNode() === options.cursorNode) {
+  if (path.getNode() === options.cursorNode && path.getValue()) {
     return concat([cursor, printed]);
   }
   return printed;

tests/cursor/jsfmt.spec.js

@@ -22,3 +22,17 @@ test("keeps cursor inside formatted node", () => {
     cursorOffset: 14 // TODO fix this
   });
 });
+
+test("doesn't insert second placeholder for nonexistent TypeAnnotation", () => {
+  const code = `
+foo('bar', cb => {
+  console.log('stuff')
+})`;
+  expect(prettier.formatWithCursor(code, { cursorOffset: 24 })).toEqual({
+    formatted: `foo("bar", cb => {
+  console.log("stuff");
+});
+`,
+    cursorOffset: 23
+  });
+});