Check if asset exists

You can use the following trick:

<#assign assetExistsPath = asset.get('/html/assets/ico_publish.png')/>
<#assign assetDoesNotExistsPath = asset.get('/html/assets/ico_publish-DOES-NOT-EXIST.png')/>
<p>assetExistsPath: ${assetExistsPath}</p>
<p>assetDoesNotExistsPath: ${assetDoesNotExistsPath}</p>

 The output of this code is:

assetExistsPath: http://<community URL>/html/assets/ico_publish.png?AE78400E7F6823769365D7E542C262A2

assetDoesNotExistsPath: http://<community URL>/html/assets/ico_publish-error.png

 You can now build a condition based on whether the checksum is present or not. It will be present when the asset exists and it will not be present if it does not. So you can test assetPath?contains("?") or you can build a function like this

<#function assetExists assetName>
 <#local fileEnding = assetName?split(".")?last />
 <#local assetPath = asset.get(assetName) />
 <#if assetPath?ends_with(fileEnding)>
   <#return false />
 </#if>  
 <#return true /> 
</#function>  

<#assign assetExistsTest = assetExists('/html/assets/ico_publish.png')/>
<#assign assetDoesNotExistsTest = assetExists('/html/assets/ico_publish-error.png')/>
<p>assetExistsTest: ${assetExistsTest?string('yes', 'no')}</p>
<p>assetDoesNotExistsTest: ${assetDoesNotExistsTest?string('yes', 'no')}</p>