Use original descriptors on implicit coercion to unit generation

compiler/ir/ir.psi2ir/src/org/jetbrains/kotlin/psi2ir/transformations/InsertImplicitCasts.kt

@@ -233,7 +233,7 @@ class InsertImplicitCasts(context: GeneratorContext) : IrElementTransformerVoid(
     }
 
     private fun IrExpression.coerceToUnit(): IrExpression {
-        val valueType = this.type.originalKotlinType!!
+        val valueType = getKotlinType(this)
 
         return if (KotlinTypeChecker.DEFAULT.isSubtypeOf(valueType, builtIns.unitType))
             this
@@ -247,6 +247,11 @@ class InsertImplicitCasts(context: GeneratorContext) : IrElementTransformerVoid(
             )
     }
 
+    private fun getKotlinType(irExpression: IrExpression) =
+        if (irExpression is IrCall)
+            irExpression.symbol.descriptor.original.returnType!!
+        else irExpression.type.originalKotlinType!!
+
     private fun KotlinType.isBuiltInIntegerType(): Boolean =
         KotlinBuiltIns.isByte(this) ||
                 KotlinBuiltIns.isShort(this) ||