src/rss_converter_twitter.com.xsl: only output channel image when it's available

Hashtag pages do not have an image usable as a channel logo, and in
cases like this the <url/> element would be empty, but this would make
the feed invalid according to https://www.feedvalidator.org

So, to produce feeds which validate, avoid outputting the whole <image/>
element when there is no suitable image to use as a channel logo.

diff --git a/src/rss_converter_twitter.com.xsl b/src/rss_converter_twitter.com.xsl
index 53bbb84..d1514c5 100644 (file)
--- a/src/rss_converter_twitter.com.xsl
+++ b/src/rss_converter_twitter.com.xsl
@@ -181,6 +181,7 @@
             </xsl:choose>
         </xsl:variable>
         <xsl:variable name="channel-link" select="//link[@rel='canonical']/@href"/>
+        <xsl:variable name="channel-image" select="//a[contains(@class, 'profile-picture')]/@href"/>
 
         <rss version="2.0">
             <xsl:attribute name="xml:base"><xsl:value-of select="$BaseURL" /></xsl:attribute>
@@ -197,17 +198,19 @@
                     <!-- The following rule should only match on hashtag URLs -->
                     <xsl:value-of select="normalize-space(//div[@class='SearchNavigation-textContainer'])"/>
                 </description>
-                <image>
-                    <title>
-                        <xsl:value-of select="$channel-title"/>
-                    </title>
-                    <link>
-                        <xsl:value-of select="$channel-link"/>
-                    </link>
-                    <url>
-                        <xsl:value-of select="//a[contains(@class, 'profile-picture')]/@href"/>
-                    </url>
-                </image>
+                <xsl:if test="$channel-image != ''">
+                    <image>
+                        <title>
+                            <xsl:value-of select="$channel-title"/>
+                        </title>
+                        <link>
+                            <xsl:value-of select="$channel-link"/>
+                        </link>
+                        <url>
+                            <xsl:value-of select="$channel-image"/>
+                        </url>
+                    </image>
+                </xsl:if>
                 <xsl:apply-templates select="//ol[@id='stream-items-id']/li[@data-item-id and @data-item-type='tweet' and not(contains(@class, 'has-profile-promoted-tweet'))]"/>
 
                 <!-- These rules will only match on permalink URLs -->