fixed bug

NULL_FOR_NONNULL_TYPE can represent type mismatch error as well
(later the whole method 'makeTraceInterceptingTypeMismatch' should be removed)

compiler/frontend/src/org/jetbrains/jet/lang/types/expressions/ExpressionTypingUtils.java

@@ -462,7 +462,7 @@ public class ExpressionTypingUtils {
             @Override
             public void report(@NotNull Diagnostic diagnostic) {
                 AbstractDiagnosticFactory factory = diagnostic.getFactory();
-                if ((factory == TYPE_MISMATCH || factory == CONSTANT_EXPECTED_TYPE_MISMATCH)
+                if ((factory == TYPE_MISMATCH || factory == CONSTANT_EXPECTED_TYPE_MISMATCH || factory == NULL_FOR_NONNULL_TYPE)
                         && diagnostic.getPsiElement() == expressionToWatch) {
                     mismatchFound[0] = true;
                 }

compiler/testData/diagnostics/tests/functionLiterals/returnNull.kt

@@ -0,0 +1,10 @@
+package m
+
+trait Element
+
+fun test(handlers: Map<String, Element.()->Unit>) {
+
+    handlers.getOrElse("name", { null })
+}
+
+fun <K,V> Map<K,V>.getOrElse(key: K, defaultValue: ()-> V) : V = throw Exception("$key $defaultValue")

compiler/tests/org/jetbrains/jet/checkers/JetDiagnosticsTestGenerated.java

@@ -2685,6 +2685,11 @@ public class JetDiagnosticsTestGenerated extends AbstractDiagnosticsTestWithEage
                 doTest("compiler/testData/diagnostics/tests/functionLiterals/NoDanglingFunctionLiteralForNestedCalls.kt");
             }
             
+            @TestMetadata("returnNull.kt")
+            public void testReturnNull() throws Exception {
+                doTest("compiler/testData/diagnostics/tests/functionLiterals/returnNull.kt");
+            }
+            
             @TestMetadata("unusedLiteral.kt")
             public void testUnusedLiteral() throws Exception {
                 doTest("compiler/testData/diagnostics/tests/functionLiterals/unusedLiteral.kt");