Fix crash getting spell-check suggestions

shell/platform/android/io/flutter/plugin/editing/SpellCheckPlugin.java

@@ -132,6 +132,11 @@ public void onGetSentenceSuggestions(SentenceSuggestionsInfo[] results) {
     ArrayList<HashMap<String, Object>> spellCheckerSuggestionSpans =
         new ArrayList<HashMap<String, Object>>();
     SentenceSuggestionsInfo spellCheckResults = results[0];
+    if (spellCheckResults == null) {
+      pendingResult.success(new ArrayList<HashMap<String, Object>>());
+      pendingResult = null;
+      return;
+    }
 
     for (int i = 0; i < spellCheckResults.getSuggestionsCount(); i++) {
       SuggestionsInfo suggestionsInfo = spellCheckResults.getSuggestionsInfoAt(i);

shell/platform/android/test/io/flutter/plugin/editing/SpellCheckPluginTest.java

@@ -247,4 +247,22 @@ public void onGetSentenceSuggestionsResultsWithSuccessAndNoResultsWhenSuggestion
 
     verify(mockResult).success(new ArrayList<HashMap<String, Object>>());
   }
+
+  @Test
+  public void onGetSentenceSuggestionsResultsWithSuccessAndNoResultsWhenSuggestionsAreInvalid2() {
+    TextServicesManager fakeTextServicesManager = mock(TextServicesManager.class);
+    SpellCheckChannel fakeSpellCheckChannel = mock(SpellCheckChannel.class);
+    SpellCheckPlugin spellCheckPlugin =
+        spy(new SpellCheckPlugin(fakeTextServicesManager, fakeSpellCheckChannel));
+    MethodChannel.Result mockResult = mock(MethodChannel.Result.class);
+    spellCheckPlugin.pendingResult = mockResult;
+
+    spellCheckPlugin.onGetSentenceSuggestions(
+        new SentenceSuggestionsInfo[] {
+          // This "suggestion" may be provided by the Samsung spell checker:
+          null
+        });
+
+    verify(mockResult).success(new ArrayList<HashMap<String, Object>>());
+  }
 }