Lookup element factory: do not use outdated descriptor

Probably #KT-20986 Fixed

idea/idea-completion/src/org/jetbrains/kotlin/idea/completion/BasicLookupElementFactory.kt

@@ -37,9 +37,11 @@ import org.jetbrains.kotlin.renderer.DescriptorRenderer
 import org.jetbrains.kotlin.resolve.DescriptorToSourceUtils
 import org.jetbrains.kotlin.resolve.DescriptorUtils
 import org.jetbrains.kotlin.resolve.descriptorUtil.isExtension
+import org.jetbrains.kotlin.resolve.descriptorUtil.module
 import org.jetbrains.kotlin.synthetic.SamAdapterExtensionFunctionDescriptor
 import org.jetbrains.kotlin.synthetic.SyntheticJavaPropertyDescriptor
 import org.jetbrains.kotlin.utils.addToStdlib.firstNotNullResult
+import javax.swing.Icon
 
 class BasicLookupElementFactory(
         private val project: Project,
@@ -163,7 +165,10 @@ class BasicLookupElementFactory(
                 lookupObject = object : DeclarationLookupObjectImpl(descriptor) {
                     override val psiElement by lazy { DescriptorToSourceUtils.getSourceFromDescriptor(descriptor) }
 
-                    override fun getIcon(flags: Int) = KotlinDescriptorIconProvider.getIcon(descriptor, psiElement, flags)
+                    override fun getIcon(flags: Int): Icon? {
+                        if (!descriptor.module.isValid) return null
+                        return KotlinDescriptorIconProvider.getIcon(descriptor, psiElement, flags)
+                    }
                 }
                 descriptor.name.asString()
             }