Handle exception and clean-up code

pkg/analyzer/lib/src/generated/engine.dart

Index: pkg/analyzer/lib/src/generated/engine.dart
diff --git a/pkg/analyzer/lib/src/generated/engine.dart b/pkg/analyzer/lib/src/generated/engine.dart
index af7eb925f53087a2f2d3f1bad227b9e01d3be4b8..75b37af269f4c967886c53a61bc5194f4172f6b1 100644
--- a/pkg/analyzer/lib/src/generated/engine.dart
+++ b/pkg/analyzer/lib/src/generated/engine.dart
@@ -1977,7 +1977,10 @@ class AnalysisContextImpl implements InternalAnalysisContext {
       if (AnalysisEngine.isHtmlFileName(sourceName)) {
         return computeHtmlElement(source);
       }
-    } on AnalysisException catch (exception) {
+    } catch (exception) {
+      // If the location cannot be decoded for some reason then the underlying
+      // cause should have been logged already and we can fall though to return
+      // null.
     }
     return null;
   }