Fix for NPE in the field creation Quick Fix.

pkg/analysis_server/lib/src/services/correction/fix_internal.dart

Index: pkg/analysis_server/lib/src/services/correction/fix_internal.dart
diff --git a/pkg/analysis_server/lib/src/services/correction/fix_internal.dart b/pkg/analysis_server/lib/src/services/correction/fix_internal.dart
index a629ad52eb6f0fadb2971edef5a8e6a08d5a9f43..ae697914485764c60eb9dae7eb814f5a08625423 100644
--- a/pkg/analysis_server/lib/src/services/correction/fix_internal.dart
+++ b/pkg/analysis_server/lib/src/services/correction/fix_internal.dart
@@ -736,8 +736,13 @@ class FixProcessor {
       staticModifier = _inStaticContext();
     }
     utils.targetClassElement = targetClassElement;
+    // prepare target ClassDeclaration
+    AstNode targetTypeNode = targetClassElement.node;
+    if (targetTypeNode is! ClassDeclaration) {
+      return;
+    }
+    ClassDeclaration targetClassNode = targetTypeNode;
     // prepare location
-    ClassDeclaration targetClassNode = targetClassElement.node;
     _FieldLocation targetLocation = _prepareNewFieldLocation(targetClassNode);
     // build method source
     String targetFile = targetClassElement.source.fullName;
@@ -861,8 +866,13 @@ class FixProcessor {
       staticModifier = _inStaticContext();
     }
     utils.targetClassElement = targetClassElement;
+    // prepare target ClassDeclaration
+    AstNode targetTypeNode = targetClassElement.node;
+    if (targetTypeNode is! ClassDeclaration) {
+      return;
+    }
+    ClassDeclaration targetClassNode = targetTypeNode;
     // prepare location
-    ClassDeclaration targetClassNode = targetClassElement.node;
     _FieldLocation targetLocation = _prepareNewGetterLocation(targetClassNode);
     // build method source
     String targetFile = targetClassElement.source.fullName;