?substring(...) argument #2 had invalid value: The index mustn't be greater than the length of the string, 0, but it was 4.

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FTL stack trace ("~" means nesting-related):
	- Failed at: ${content.attrs.ksrqq!?substring(0, 4)}  [in template "json://{\"siteId\":\"0035\",\"category\":\"content\",\"tags\":\"pt\",\"name\":\"pt-考试院稿件\"}_en_US" at line 140, column 37]
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