Only attempt loading img URL with filename and appropriate extension

updates #1228

dist/converse.js

@@ -82094,13 +82094,24 @@ var __WEBPACK_AMD_DEFINE_FACTORY__, __WEBPACK_AMD_DEFINE_ARRAY__, __WEBPACK_AMD_
      */
     const __ = _converse.__;
     const list = obj.textContent.match(URL_REGEX) || [];
-    return Promise.all(_.map(list, url => new Promise((resolve, reject) => isImage(url).then(function (img) {
+    return Promise.all(_.map(list, url => new Promise((resolve, reject) => {
+      const uri = new URI(url),
+            filename = uri.filename(),
+            lower_filename = filename.toLowerCase();
+
+      if (!_.includes(["https", "http"], uri.protocol().toLowerCase())) {
+        return resolve();
+      }
+
+      if (lower_filename.endsWith('jpg') || lower_filename.endsWith('jpeg') || lower_filename.endsWith('png') || lower_filename.endsWith('gif') || lower_filename.endsWith('svg')) {
+        return isImage(url).then(img => {
           const i = new Image();
           i.src = img.src;
           i.addEventListener('load', resolve); // We also resolve for non-images, otherwise the
           // Promise.all resolves prematurely.
 
           i.addEventListener('error', resolve);
+          const __ = _converse.__;
 
           _.each(sizzle(`a[href="${url}"]`, obj), a => {
             a.outerHTML = tpl_image({
@@ -82108,7 +82119,11 @@ var __WEBPACK_AMD_DEFINE_FACTORY__, __WEBPACK_AMD_DEFINE_ARRAY__, __WEBPACK_AMD_
               'label_download': __('Download')
             });
           });
-    }).catch(resolve))));
+        }).catch(resolve);
+      } else {
+        return resolve();
+      }
+    })));
   };
 
   u.renderFileURL = function (_converse, url) {

src/utils/core.js

@@ -288,8 +288,18 @@
         const list = obj.textContent.match(URL_REGEX) || [];
         return Promise.all(
             _.map(list, (url) =>
-                new Promise((resolve, reject) =>
-                    isImage(url).then(function (img) {
+                new Promise((resolve, reject) => {
+                    const uri = new URI(url),
+                        filename = uri.filename(),
+                        lower_filename = filename.toLowerCase();
+                    if (!_.includes(["https", "http"], uri.protocol().toLowerCase())) {
+                        return resolve();
+                    }
+                    if (lower_filename.endsWith('jpg') || lower_filename.endsWith('jpeg') ||
+                            lower_filename.endsWith('png') || lower_filename.endsWith('gif') ||
+                            lower_filename.endsWith('svg')) {
+
+                        return isImage(url).then(img => {
                             const i = new Image();
                             i.src = img.src;
                             i.addEventListener('load', resolve);
@@ -297,6 +307,7 @@
                             // Promise.all resolves prematurely.
                             i.addEventListener('error', resolve);
 
+                            const { __ } = _converse;
                             _.each(sizzle(`a[href="${url}"]`, obj), (a) => {
                                 a.outerHTML= tpl_image({
                                     'url': url,
@@ -304,7 +315,10 @@
                                 })
                             });
                         }).catch(resolve)
-                )
+                    } else {
+                        return resolve();
+                    }
+                })
             )
         )
     };