Handle invalid markdown

In these cases we just try to fetch the body the best we can and ignore
all the keys.

This should give us more info about #4

lib/storage/serializers.dart

@@ -26,12 +26,18 @@ class MarkdownYAMLSerializer implements NoteSerializer {
   Note decode(String str) {
     if (str.startsWith("---\n")) {
       var parts = str.split("---\n");
-
-      var yamlMap = loadYaml(parts[1]);
       var map = <String, dynamic>{};
-      yamlMap.forEach((key, value) {
-        map[key] = value;
-      });
+
+      try {
+        var yamlMap = loadYaml(parts[1]);
+        yamlMap.forEach((key, value) {
+          map[key] = value;
+        });
+      } catch (err, stack) {
+        print(
+            'MarkdownYAMLSerializer::decode (${parts[1]}) -> ${err.toString()}');
+        print(stack.toString());
+      }
       map['body'] = parts[2].trimLeft();
 
       return Note.fromJson(map);

test/serializers_test.dart

@@ -31,6 +31,20 @@ void main() {
       expect(note2, note);
     });
 
+    test('Markdown Serializer with invalid Markdown', () {
+      var inputNoteStr = """---
+type
+---
+
+Alright.""";
+
+      var serializer = MarkdownYAMLSerializer();
+      var note = serializer.decode(inputNoteStr);
+      var actualStr = "Alright.";
+
+      expect(actualStr, note.body);
+    });
+
     /*
     test('Markdown Serializer YAML Order', () {
       var str = """---