fix: IndexError when only URL in long description (#190)

* fix: IndexError with only URL in long description

* test: for IndexError with only URL in long description

src/docformatter/syntax.py

@@ -338,8 +338,9 @@ def do_split_description(
                 )
             )
 
-            if _lines[-1] == "":
-                _lines.pop(-1)
+            with contextlib.suppress(IndexError):
+                if _lines[-1] == "":
+                    _lines.pop(-1)
 
             # Add the URL.
             _lines.append(

tests/test_format_docstring.py

@@ -1298,6 +1298,43 @@ def test_format_docstring_with_short_link(
             INDENTATION, docstring.strip()
         )
 
+    @pytest.mark.unit
+    @pytest.mark.parametrize(
+        "args",
+        [["--wrap-descriptions", "72", ""]],
+    )
+    def test_format_docstring_with_only_link_in_description(
+        self,
+        test_args,
+        args,
+    ):
+        """No index error when only link in long description.
+
+        See issue #189.
+        """
+        uut = Formatter(
+            test_args,
+            sys.stderr,
+            sys.stdin,
+            sys.stdout,
+        )
+
+        docstring = '''\
+    """This method doesn't do anything.
+
+    https://example.com/this-is-just-a-long-url/designed-to-trigger/the-wrapping-of-the-description
+    """
+'''
+
+        assert '''\
+"""This method doesn\'t do anything.
+
+    https://example.com/this-is-just-a-long-url/designed-to-trigger/the-wrapping-of-the-description
+    """\
+''' == uut._do_format_docstring(
+            INDENTATION, docstring.strip()
+        )
+
     @pytest.mark.unit
     @pytest.mark.parametrize(
         "args",