[FIR] Fix crash on assignment expression with incorrect lvalue with LT mode

^KT-65241 Fixed

compiler/testData/diagnostics/tests/exceptions/assignmentWithIncorrectLValue.fir.kt

@@ -0,0 +1,7 @@
+// ISSUE: KT-65241
+
+object A
+
+fun test() {
+    A.<!SYNTAX!>else<!> = <!ASSIGNMENT_TYPE_MISMATCH!>42<!>
+}

compiler/testData/diagnostics/tests/exceptions/assignmentWithIncorrectLValue.kt

@@ -0,0 +1,7 @@
+// ISSUE: KT-65241
+
+object A
+
+fun test() {
+    A.<!SYNTAX!>else<!> = 42
+}

compiler/testData/integration/smoke/syntaxErrors/test.compile.expected

@@ -3,6 +3,9 @@ ERR:
 test.kt:4:13: error: classifier 'class System : Any' does not have a companion object, so it cannot be used as an expression.
     val s = System.in
             ^^^^^^
+test.kt:4:13: error: syntax error: Qualified expression without selector.
+    val s = System.in
+            ^^^^^^^^^
 test.kt:4:20: error: syntax error: Expecting an element.
     val s = System.in
                    ^^