Do not check argumentMapping.isError()

Argument matching status can be considered an "error" in resolve,
even though it is not a compilation error and doesn't prevent code
from being generated.
Actually, we should only check if the argument matching status is
ArgumentMatch.

 #KT-18294 Fixed

compiler/testData/ir/irText/expressions/argumentMappedWithError.kt

@@ -0,0 +1,9 @@
+fun <R : Number> Number.convert(): R = TODO()
+
+fun foo(arg: Number) {
+}
+
+fun main(args: Array<String>) {
+    val x: Int = 0
+    foo(x.convert())
+}