Unused Symbol: Check descriptor before creating light class to prevent InvalidMirrorException on red code

idea/testData/inspections/unusedSymbol/class/BadCodeNoExceptions.kt

@@ -0,0 +1,6 @@
+// Closing brace is intentionally missed
+val id = array("kotlin.FlexibleType"
+
+private class Some() {
+    override fun foo() = 1
+}

idea/testData/inspections/unusedSymbol/class/inspectionData/expected.xml

@@ -47,4 +47,12 @@
     <problem_class severity="WARNING" attribute_key="NOT_USED_ELEMENT_ATTRIBUTES">Unused Symbol</problem_class>
     <description>Class 'B' is never used</description>
   </problem>
+  <problem>
+    <file>BadCodeNoExceptions.kt</file>
+    <line>2</line>
+    <module>light_idea_test_case</module>
+    <entry_point TYPE="file" FQNAME="temp:///src/badCodeNoExceptions.kt" />
+    <problem_class severity="WARNING" attribute_key="NOT_USED_ELEMENT_ATTRIBUTES">Unused Symbol</problem_class>
+    <description>Property 'id' is never used</description>
+  </problem>
 </problems>