PSI2IR: ignore enum annotation arguments of error type

Similar to references to error type, this may happen if library A uses
an entity from library B annotated with an annotation from C, but A is
compiled without C on the classpath.

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/ConstantValueGenerator.kt

@@ -77,8 +77,8 @@ class ConstantValueGenerator(
                     startOffset, endOffset,
                     constantType,
                     arrayElementType.toIrType(),
-                    constantValue.value.map {
-                        generateConstantValueAsExpression(startOffset, endOffset, it, null)
+                    constantValue.value.mapNotNull {
+                        generateConstantOrAnnotationValueAsExpression(startOffset, endOffset, it, null)
                     }
                 )
             }
@@ -90,6 +90,14 @@ class ConstantValueGenerator(
                 if (enumEntryDescriptor !is ClassDescriptor) {
                     throw AssertionError("Enum entry $enumEntryDescriptor should be a ClassDescriptor")
                 }
+                if (!DescriptorUtils.isEnumEntry(enumEntryDescriptor)) {
+                    // Error class descriptor for an unresolved entry.
+                    // TODO this `null` may actually reach codegen if the annotation is on an interface member's default implementation,
+                    //      as any bridge generated in an implementation of that interface will have a copy of the annotation. See
+                    //      `missingEnumReferencedInAnnotationArgumentIr` in `testData/compileKotlinAgainstCustomBinaries`: replace
+                    //      `open class B` with `interface B` and watch things break. (`KClassValue` below likely has a similar problem.)
+                    return null
+                }
                 IrGetEnumValueImpl(
                     startOffset, endOffset,
                     constantType,
@@ -115,6 +123,8 @@ class ConstantValueGenerator(
                 }
             }
 
+            is ErrorValue -> null
+
             else -> TODO("Unexpected constant value: ${constantValue.javaClass.simpleName} $constantValue")
         }
     }