diff --git a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/utils/IrResolveUtils.kt b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/utils/IrResolveUtils.kt
index 96218ab48bf..81001d03079 100644
--- a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/utils/IrResolveUtils.kt
+++ b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/utils/IrResolveUtils.kt
@@ -10,6 +10,7 @@ import org.jetbrains.kotlin.ir.declarations.IrConstructor
 import org.jetbrains.kotlin.ir.declarations.IrFunction
 import org.jetbrains.kotlin.ir.declarations.IrSimpleFunction
 import org.jetbrains.kotlin.ir.util.collectRealOverrides
+import org.jetbrains.kotlin.ir.util.render
 
 val IrFunction.realOverrideTarget: IrFunction
     get() = when (this) {
@@ -21,5 +22,6 @@ val IrFunction.realOverrideTarget: IrFunction
 val IrSimpleFunction.realOverrideTarget: IrSimpleFunction
     get(): IrSimpleFunction {
         val realOverrides = collectRealOverrides()
-        return realOverrides.find { it.modality != Modality.ABSTRACT } ?: realOverrides.first()
+        return realOverrides.find { it.modality != Modality.ABSTRACT } ?: realOverrides.firstOrNull() ?:
+                error("No real override target found for ${this.render()}")
     }
\ No newline at end of file
diff --git a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/utils/NameTables.kt b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/utils/NameTables.kt
index f827fed56f8..4f9169141c2 100644
--- a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/utils/NameTables.kt
+++ b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/utils/NameTables.kt
@@ -12,10 +12,7 @@ import org.jetbrains.kotlin.ir.backend.js.JsLoweredDeclarationOrigin
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.expressions.IrLoop
 import org.jetbrains.kotlin.ir.types.isUnit
-import org.jetbrains.kotlin.ir.util.fqNameWhenAvailable
-import org.jetbrains.kotlin.ir.util.isEffectivelyExternal
-import org.jetbrains.kotlin.ir.util.isEnumClass
-import org.jetbrains.kotlin.ir.util.isInlined
+import org.jetbrains.kotlin.ir.util.*
 import org.jetbrains.kotlin.ir.visitors.IrElementVisitorVoid
 import org.jetbrains.kotlin.ir.visitors.acceptChildrenVoid
 import org.jetbrains.kotlin.ir.visitors.acceptVoid
@@ -279,7 +276,7 @@ class NameTables(packages: List<IrPackageFragment>) {
         if (name == null && signature is ParameterTypeBasedSignature && signature.suggestedName.startsWith("invoke"))
             return signature.suggestedName
         require(name != null) {
-            "Can't find name for member function $function"
+            "Can't find name for member function ${function.render()}"
         }
         return name
     }