fix(rule): Ignore empty paragraph (#1)

* Ignore empty Paragraph. Ex) '<p></p>'

When applying `textlint-rule-prefer-tari-tari` to HTML, an error
occurred.

`` `console
✖ Stack trace
TypeError: Can not read property 'children' of undefined
    at
/usr/local/lib/node_modules/textlint-rule-prefer-tari-tari/lib/textlint-
rule-prefer-tari-tari.js:56:44
    at <anonymous>
    at process._ tickCallback (internal / process / next_tick.js: 188:
7)
`` `

I checked the contents of the NODE where the error occurred.

`` `console
### NODE
{type: 'Paragraph',
  tagName: 'p',
  properties: {},
  children: [],
  loc:
   {start: {line: 19, column: 12},
     end: {line: 19, column: 19}},
  range: [50138, 50145],
  raw: '<p> </ p>'}
### CST
{type: 'RootNode', children: [], position: {}}
### CST.children
[]
`` `

Fixed the program to ignore empty Paragraph like `<p> </ p>`.

* Merge upstream

* Merge upstream

* Merge upstream

* Merge upstream

* Update textlint-rule-prefer-tari-tari.js

* Update textlint-rule-prefer-tari-tari.js

Author: kemsakurai

src/textlint-rule-prefer-tari-tari.js

@@ -41,6 +41,10 @@ const report = context => {
                 const source = new StringSource(node);
                 const text = source.toString();
                 const CST = japaneseParser.parse(text);
+                // Ignore empty Paragraph. Ex) '<p></p>'
+                if (typeof CST.children === "undefined" || CST.children.length == 0) {
+                    return;
+                }
                 const sentences = CST.children[0].children;
                 const isSameNode = (resultsA, resultsB) => {
                     return resultsA.some(resultA => {