[NI] Fix reporting smartcast diagnostics for intersection types

#KT-30826 Fixed

compiler/testData/diagnostics/tests/smartCasts/intersectionScope/unstableSmartCast.kt

@@ -31,8 +31,8 @@ fun test() {
         x.foo().checkType { _<CharSequence?>() }
         x.baz("")
         x.baz(1).checkType { _<Unit>() }
-        <!OI;SMARTCAST_IMPOSSIBLE!>x<!>.baz(1, 2)
+        <!SMARTCAST_IMPOSSIBLE!>x<!>.baz(1, 2)
 
-        <!OI;SMARTCAST_IMPOSSIBLE!>x<!>.foobar().checkType { _<String>() }
+        <!SMARTCAST_IMPOSSIBLE!>x<!>.foobar().checkType { _<String>() }
     }
 }

compiler/testData/diagnostics/tests/smartCasts/kt30826.kt

@@ -0,0 +1,19 @@
+// !WITH_NEW_INFERENCE
+// Issue: KT-30826
+
+interface I1
+interface I2 {
+    fun foo() {}
+}
+
+class A : I1, I2
+
+fun foo(x: I1?) {
+    var y = x
+    y as I2
+    val bar = {
+        <!SMARTCAST_IMPOSSIBLE!>y<!>.foo() // NPE in NI, smartcast impossible in OI
+    }
+    y = null
+    bar()
+}

compiler/testData/diagnostics/tests/smartCasts/kt30826.txt

@@ -0,0 +1,24 @@
+package
+
+public fun foo(/*0*/ x: I1?): kotlin.Unit
+
+public final class A : I1, I2 {
+    public constructor A()
+    public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun foo(): kotlin.Unit
+    public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface I1 {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface I2 {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open fun foo(): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}