Error on 'if' without an 'else' branch when used as an expression

idea/testData/intentions/swapBinaryExpression/is.kt

@@ -1,4 +1,5 @@
 // IS_APPLICABLE: false
+// ERROR: 'if' must have both main and 'else' branches if used as an expression
 // ERROR: Expression 'if "test" is String' of type 'kotlin.Unit' cannot be invoked as a function. The function invoke() is not found
 
 fun doSomething<T>(a: T) {}