Improve debuggability for compiler crash when using tasty reflect

Without the change, we get an error message like the following:

```
1 |def test(x: Int) = foo(x)
  |                   ^^^^^^
  |An exception occurred while executing macro expansion
  |assertion failed: no overloads available for > on Int with targs: ; args: x of types rhsTpe$_$1(x); expectedType: ?.all alternatives: def >(x: Double): Boolean, def >(x: Float): Boolean, def >(x: Long): Boolean, def >(x: Int): Boolean, def >(x: Char): Boolean, def >(x: Short): Boolean, def >(x: Byte): Boolean
```

With the change, mysterious type `rhsTpe$_$1(x)` is replaced with the type `String`.

Author: liufengyun

compiler/src/dotty/tools/dotc/ast/tpd.scala

@@ -1129,7 +1129,7 @@ object tpd extends Trees.Instance[Type] with TypedTreeInfo {
         val alternatives = ctx.typer.resolveOverloaded(allAlts, proto)
         assert(alternatives.size == 1,
           i"${if (alternatives.isEmpty) "no" else "multiple"} overloads available for " +
-          i"$method on ${receiver.tpe.widenDealiasKeepAnnots} with targs: $targs%, %; args: $args%, % of types ${args.tpes}%, %; expectedType: $expectedType." +
+          i"$method on ${receiver.tpe.widenDealiasKeepAnnots} with targs: $targs%, %; args: $args%, % of types ${args.tpes.map(_.widenDealiasKeepAnnots)}%, %; expectedType: $expectedType." +
           i"all alternatives: ${allAlts.map(_.symbol.showDcl).mkString(", ")}\n" +
           i"matching alternatives: ${alternatives.map(_.symbol.showDcl).mkString(", ")}.") // this is parsed from bytecode tree. there's nothing user can do about it
         alternatives.head