Fix LUB computation in face of errors in code (issue 26631)

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

Index: pkg/analyzer/lib/src/generated/static_type_analyzer.dart
diff --git a/pkg/analyzer/lib/src/generated/static_type_analyzer.dart b/pkg/analyzer/lib/src/generated/static_type_analyzer.dart
index fefd3ebca75ef140371cec76fc2601ee7985cce1..8699787fdab54f78fc5c6451af5e60a80bf3d27c 100644
--- a/pkg/analyzer/lib/src/generated/static_type_analyzer.dart
+++ b/pkg/analyzer/lib/src/generated/static_type_analyzer.dart
@@ -662,8 +662,11 @@ class StaticTypeAnalyzer extends SimpleAstVisitor<Object> {
       // elements
       if (node.elements.isNotEmpty) {
         // Infer the list type from the arguments.
-        DartType staticType =
-            node.elements.map((e) => e.staticType).reduce(_leastUpperBound);
+        Iterable<DartType> types = node.elements.map((e) => e.staticType).where((t) => t != null);
+        if (types.isEmpty) {
+          return null;
+        }
+        DartType staticType = types.reduce(_leastUpperBound);
         if (staticType.isBottom) {
           staticType = _dynamicType;
         }