The following has evaluated to null or missing:
==> content.source  [in template "SelectShanDongGermany_pc/template/list.template.html" at line 48, column 112]

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Tip: It's the step after the last dot that caused this error, not those before it.
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Tip: If the failing expression is known to legally refer to something that's sometimes null or missing, either specify a default value like myOptionalVar!myDefault, or use <#if myOptionalVar??>when-present<#else>when-missing</#if>. (These only cover the last step of the expression; to cover the whole expression, use parenthesis: (myOptionalVar.foo)!myDefault, (myOptionalVar.foo)??
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FTL stack trace ("~" means nesting-related):
	- Failed at: ${content.source}  [in template "SelectShanDongGermany_pc/template/list.template.html" at line 48, column 110]
	- Reached through: @cms_content catalogid="${Catalog.cat...  [in template "SelectShanDongGermany_pc/template/list.template.html" at line 41, column 18]
----

Java stack trace (for programmers):
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freemarker.core.InvalidReferenceException: [... Exception message was already printed; see it above ...]
	at freemarker.core.InvalidReferenceException.getInstance(InvalidReferenceException.java:134)
	at freemarker.core.EvalUtil.coerceModelToTextualCommon(EvalUtil.java:481)
	at freemarker.core.EvalUtil.coerceModelToStringOrMarkup(EvalUtil.java:401)
	at freemarker.core.EvalUtil.coerceModelToStringOrMarkup(EvalUtil.java:370)
	at freemarker.core.DollarVariable.calculateInterpolatedStringOrMarkup(DollarVariable.java:104)
	at freemarker.core.DollarVariable.accept(DollarVariable.java:63)
	at freemarker.core.Environment.visit(Environment.java:371)
	at freemarker.core.IteratorBlock$IterationContext.executedNestedContentForCollOrSeqListing(IteratorBlock.java:321)
	at freemarker.core.IteratorBlock$IterationContext.executeNestedContent(IteratorBlock.java:271)
	at freemarker.core.IteratorBlock$IterationContext.accept(IteratorBlock.java:244)
	at freemarker.core.Environment.visitIteratorBlock(Environment.java:645)
	at freemarker.core.IteratorBlock.acceptWithResult(IteratorBlock.java:108)
	at freemarker.core.IteratorBlock.accept(IteratorBlock.java:94)
	at freemarker.core.Environment.visit(Environment.java:371)
	at freemarker.core.Environment$NestedElementTemplateDirectiveBody.render(Environment.java:3423)
	at com.ruoyi.common.staticize.tag.AbstractTag.onTagEnd(AbstractTag.java:81)
	at com.ruoyi.common.staticize.tag.AbstractTag.execute(AbstractTag.java:50)
	at freemarker.core.Environment.visit(Environment.java:452)
	at freemarker.core.UnifiedCall.accept(UnifiedCall.java:102)
	at freemarker.core.Environment.visit(Environment.java:335)
	at freemarker.core.Environment.visit(Environment.java:341)
	at freemarker.core.Environment.process(Environment.java:314)
	at com.ruoyi.common.staticize.StaticizeService.process(StaticizeService.java:78)
	at com.ruoyi.contentcore.service.impl.PublishServiceImpl.doCatalogStaticize(PublishServiceImpl.java:423)
	at com.ruoyi.contentcore.service.impl.PublishServiceImpl.catalogStaticize(PublishServiceImpl.java:351)
	at com.ruoyi.contentcore.service.impl.PublishServiceImpl$4.run0(PublishServiceImpl.java:336)
	at com.ruoyi.common.async.AsyncTask.run(AsyncTask.java:90)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
	at java.base/java.lang.Thread.run(Thread.java:833)