Fix exception when checking URL validity

Author: Christopher Raquet

src/main/java/edu/kit/datamanager/ro_crate/entities/data/DataEntity.java

@@ -118,7 +118,7 @@ public T addContent(Path path, String id) {
         public T addContent(URI uri) {
             if (isUrl(uri.toString())) {
                 this.setId(uri.toString());
-            }
+            } else throw new IllegalArgumentException("This Data Entity remote ID does not resolve to a valid URL.");
             return self();
         }
 

src/main/java/edu/kit/datamanager/ro_crate/special/UriUtil.java

@@ -56,7 +56,11 @@ public static boolean isValidUri(String uri) {
      * @return true if it is a url, false otherwise.
      */
     public static boolean isUrl(String uri) {
-        return asUrl(uri).isPresent();
+        try {
+            return asUrl(uri).isPresent();
+        } catch (Exception e) {
+            return false;
+        }
     }
 
     /**