fix crash associated with trailing/repeating commas within srcset

src/html.rs

@@ -159,10 +159,12 @@ pub fn embed_srcset(
     let srcset_items: Vec<&str> = srcset.split(',').collect();
     for srcset_item in srcset_items {
         let parts: Vec<&str> = srcset_item.trim().split_whitespace().collect();
-        let path = parts[0].trim();
-        let descriptor = if parts.len() > 1 { parts[1].trim() } else { "" };
-        let srcset_real_item = SrcSetItem { path, descriptor };
-        array.push(srcset_real_item);
+        if parts.len() > 0 {
+            let path = parts[0].trim();
+            let descriptor = if parts.len() > 1 { parts[1].trim() } else { "" };
+            let srcset_real_item = SrcSetItem { path, descriptor };
+            array.push(srcset_real_item);
+        }
     }
 
     let mut result: String = str!();

src/tests/html/embed_srcset.rs

@@ -29,3 +29,35 @@ mod passing {
         );
     }
 }
+
+//  ███████╗ █████╗ ██╗██╗     ██╗███╗   ██╗ ██████╗
+//  ██╔════╝██╔══██╗██║██║     ██║████╗  ██║██╔════╝
+//  █████╗  ███████║██║██║     ██║██╔██╗ ██║██║  ███╗
+//  ██╔══╝  ██╔══██║██║██║     ██║██║╚██╗██║██║   ██║
+//  ██║     ██║  ██║██║███████╗██║██║ ╚████║╚██████╔╝
+//  ╚═╝     ╚═╝  ╚═╝╚═╝╚══════╝╚═╝╚═╝  ╚═══╝ ╚═════╝
+
+#[cfg(test)]
+mod failing {
+    use reqwest::blocking::Client;
+    use std::collections::HashMap;
+
+    use crate::html;
+    use crate::opts::Options;
+
+    #[test]
+    fn trailing_comma() {
+        let cache = &mut HashMap::new();
+        let client = Client::new();
+        let srcset_value = "small.png 1x, large.png 2x,";
+        let mut options = Options::default();
+        options.no_images = true;
+        options.silent = true;
+        let embedded_css = html::embed_srcset(cache, &client, "", &srcset_value, &options, 0);
+
+        assert_eq!(
+            format!("{} 1x, {} 2x", empty_image!(), empty_image!()),
+            embedded_css
+        );
+    }
+}