YAML parsing error when inserting template

[Yodo9000]

Plugin information

• OS: Windows 10
• Templater version: 2.18.1
• Obsidian version: 1.12.4
• Trigger Templater on new file creation:
  • Apply the following template:

    ---
    aliases:
    - %
    ---
    

Describe the bug
The newly created file remains empty. The console shows the following:

app.js:1 Uncaught (in promise) YAMLParseError: Plain value cannot start with directive indicator character % at line 2, column 3:

- %
  ^

    at onError (app.js:1:1277524)
    at c (app.js:1:1269939)
    at app.js:1:1270259
    at US (app.js:1:1270333)
    at YS (app.js:1:1272698)
    at $S (app.js:1:1274871)
    at app.js:1:1263551
    at qS (app.js:1:1263682)
    at app.js:1:1275452
    at $S (app.js:1:1275996)

Expected behavior
The template to be inserted into the file, even if the YAML is incorrect - the core Template plugin does do this.

Additional context

Initially my template was the following:

---
aliases:
- %% unsure if to add aliases %%
---