Fix util.getStringWidth for falsy input (#3092)

src/util.js

@@ -740,6 +740,10 @@ function splitText(text) {
 }
 
 function getStringWidth(text) {
+  if (!text) {
+    return 0;
+  }
+
   // emojis are considered 2-char width for consistency
   // see https://github.com/sindresorhus/string-width/issues/11
   // for the reason why not implemented in `string-width`

tests/markdown_table/__snapshots__/jsfmt.spec.js.snap

@@ -33,6 +33,19 @@ exports[`emoji.md 1`] = `
 
 `;
 
+exports[`empty.md 1`] = `
+Foo | Bar
+--- | ---
+X   |
+Y   |
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+| Foo | Bar |
+| --- | --- |
+| X   |
+| Y   |
+
+`;
+
 exports[`escape.md 1`] = `
 | a | b | c |
 |:--|:-:|--:|

tests/markdown_table/empty.md

@@ -0,0 +1,4 @@
+Foo | Bar
+--- | ---
+X   |
+Y   |

tests_config/run_spec.js

@@ -18,6 +18,7 @@ function run_spec(dirname, options, additionalParsers) {
     if (
       extname(filename) !== ".snap" &&
       fs.lstatSync(path).isFile() &&
+      filename[0] !== "." &&
       filename !== "jsfmt.spec.js"
     ) {
       let rangeStart = 0;