fix: add null checks in HtmlMovementMethod to prevent crashes (#108)

- Add null check for imgs collection before iterating
- Add null check for currentImg before comparison
- Add null check for imgs.get(i) and its getUrl() method
- Prevents NullPointerException when clicking on image spans
- Fixes crash reported in Google Play Console at line 215

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-authored-by: Claude <noreply@anthropic.com>

Author: graycreate

app/src/main/java/me/ghui/v2er/widget/richtext/HtmlMovementMethod.java

@@ -211,10 +211,14 @@ private void onSpanClick(CharacterStyle span) {
         } else if (span instanceof ImageSpan) {
             String currentImg = ((ImageSpan) span).getSource();
             int index = 0;
-            for (int i = 0; i < imgs.size(); i++) {
-                if (currentImg.equals(imgs.get(i).getUrl())) {
-                    index = i;
-                    break;
+            // Add null checks to prevent NullPointerException
+            if (imgs != null && currentImg != null) {
+                for (int i = 0; i < imgs.size(); i++) {
+                    String imgUrl = imgs.get(i) != null ? imgs.get(i).getUrl() : null;
+                    if (currentImg.equals(imgUrl)) {
+                        index = i;
+                        break;
+                    }
                 }
             }
             ImagesInfo imagesInfo = new ImagesInfo(index, imgs);