[NI] Make subtyping algorithm more robust to error types

During subtyping/incorporation we transform types (e.g. changing nullability,
 form of the type) and, basically, we're doing this to some FIXPOINT.
 It's important that we use `KotlinType.hashCode()` to compare types, but
 for error types hashCode is a hashCode of its supertype and, for example,
 `makeNullableAsSpecified` method recreate type every time. So, we continue
 to generate new constraints and we'll never stop incorporation algorithm

compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java

@@ -9565,6 +9565,11 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                     runTest("compiler/testData/diagnostics/tests/inference/constraints/equalityConstraintOnNullableType.kt");
                 }
 
+                @TestMetadata("errorUpperBoundConstraint.kt")
+                public void testErrorUpperBoundConstraint() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/inference/constraints/errorUpperBoundConstraint.kt");
+                }
+
                 @TestMetadata("ignoreConstraintFromImplicitInNothing.kt")
                 public void testIgnoreConstraintFromImplicitInNothing() throws Exception {
                     runTest("compiler/testData/diagnostics/tests/inference/constraints/ignoreConstraintFromImplicitInNothing.kt");