adding a null check for avoiding a crash if node is empty

Author: Narendra7479

android/src/main/java/iyegoroff/RNTextGradient/RNShadowTextGradient.java

@@ -91,18 +91,22 @@ public void onCollectExtraUpdates(UIViewOperationQueue uiViewOperationQueue) {
 
   private void updateGradient() {
     if (!isVirtual()) {
-      String fieldName = "mPreparedSpannableText";
-        
-      setParentFieldValue(
-        this,
-        fieldName,
-        spannableWithGradient(
-          (Spannable) getParentFieldValue(this, fieldName),
-          this,
-          getLayoutWidth(),
-          getLayoutHeight()
-        )
-      );  
+
+      try {
+        String fieldName = "mPreparedSpannableText";
+
+        setParentFieldValue(
+                this,
+                fieldName,
+                spannableWithGradient(
+                        (Spannable) getParentFieldValue(this, fieldName),
+                        this,
+                        getLayoutWidth(),
+                        getLayoutHeight()
+                )
+        );
+      } catch (Throwable throwable) {
+      }
     }
   }