Remove handler for erased params in synthesizer

Author: natsukagami

compiler/src/dotty/tools/dotc/typer/Synthesizer.scala

@@ -109,13 +109,10 @@ class Synthesizer(typer: Typer)(using @constructorOnly c: Context):
       case AppliedType(_, funArgs @ fun :: tupled :: Nil) =>
         def functionTypeEqual(baseFun: Type, actualArgs: List[Type],
             actualRet: Type, expected: Type) =
-          val efp = defn.erasedFunctionParameters(baseFun)
-          assert(efp.size == 1)
-          val erasedParams = actualArgs.map(_ => efp(0))
           expected =:= defn.FunctionOf(actualArgs, actualRet,
-            defn.isContextFunctionType(baseFun), erasedParams)
+            defn.isContextFunctionType(baseFun), List() /* erased functions not supported */)
         val arity: Int =
-          if defn.isErasedFunctionType(fun) || defn.isErasedFunctionType(fun) then -1 // TODO support?
+          if defn.isErasedFunctionType(fun) then -1 // TODO support?
           else if defn.isFunctionType(fun) then
             // TupledFunction[(...) => R, ?]
             fun.dropDependentRefinement.dealias.argInfos match