StringIndexOutOfBoundsException on empty ordered list input.

[jleyba]

Using com.atlassian.commonmark:commonmark:0.1.0:

import static org.junit.Assert.assertEquals;

import org.commonmark.html.HtmlRenderer;
import org.commonmark.node.Node;
import org.commonmark.parser.Parser;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;

@RunWith(JUnit4.class)
public class MarkdownTest {
  @Test
  public void shouldWork() {
    Parser parser = Parser.builder().build();
    Node root = parser.parse("2.");

    HtmlRenderer renderer = HtmlRenderer.builder().escapeHtml(false).build();
    String html = renderer.render(root);

    assertEquals(
        "<ol start=\"2\">\n" +
            "<li></li>\n" +
            "</ol>",
        html);
  }
}

The test above fails with:

java.lang.StringIndexOutOfBoundsException: String index out of range: 2
  at java.lang.String.charAt(String.java:658)
  at org.commonmark.internal.util.Substring.charAt(Substring.java:32)
  at java.lang.Character.codePointAt(Character.java:4668)
  at org.commonmark.internal.util.Parsing.isLetter(Parsing.java:55)
  at org.commonmark.internal.DocumentParser.incorporateLine(DocumentParser.java:194)
  at org.commonmark.internal.DocumentParser.parse(DocumentParser.java:83)
  at org.commonmark.parser.Parser.parse(Parser.java:45)
  at MarkdownTest.shouldWork(MarkdownTest.java:32)

For reference, here's the output for commonmark.js: http://spec.commonmark.org/dingus/?text=2.

Edit Fixed rendering of dingus link

[robinst]

Thanks for the report! This has already been fixed by 5a2b391 on master, but I'll add your test case to make sure there won't be a regression.

[robinst]

Fix released in 0.2.0.