Don't typeAhead erroneous parsing trees related to export statements

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

@@ -1131,7 +1131,7 @@ class Namer { typer: Typer =>
     private def exportForwarders(exp: Export, pathMethod: Symbol)(using Context): List[tpd.MemberDef] =
       val buf = new mutable.ListBuffer[tpd.MemberDef]
       val Export(expr, selectors) = exp
-      if expr.isEmpty then
+      if expr.isEmpty || selectors.exists(_.imported.name == nme.ERROR) then
         report.error(em"Export selector must have prefix and `.`", exp.srcPos)
         return Nil
 

tests/neg/i20511-1.check

@@ -0,0 +1,32 @@
+-- [E083] Type Error: tests/neg/i20511-1.scala:7:7 ---------------------------------------------------------------------
+7 |export toppingPrice.apply, crustPrice.apply, crustPrice.unlift // error // error // error // error // error
+  |       ^^^^^^^^^^^^
+  |       Int => Double is not a valid export prefix, since it is not an immutable path
+  |
+  | longer explanation available when compiling with `-explain`
+-- [E083] Type Error: tests/neg/i20511-1.scala:7:27 --------------------------------------------------------------------
+7 |export toppingPrice.apply, crustPrice.apply, crustPrice.unlift // error // error // error // error // error
+  |                           ^^^^^^^^^^
+  |                           Any is not a valid export prefix, since it is not an immutable path
+  |
+  | longer explanation available when compiling with `-explain`
+-- Error: tests/neg/i20511-1.scala:7:38 --------------------------------------------------------------------------------
+7 |export toppingPrice.apply, crustPrice.apply, crustPrice.unlift // error // error // error // error // error
+  |                                      ^^^^^
+  |                                      no eligible member apply at {
+  |                                        def $anonfun(crustType: Double): Double = pakiet.crustPrice(crustType)
+  |                                        closure(pakiet.$anonfun:Any)
+  |                                      }
+-- [E083] Type Error: tests/neg/i20511-1.scala:7:45 --------------------------------------------------------------------
+7 |export toppingPrice.apply, crustPrice.apply, crustPrice.unlift // error // error // error // error // error
+  |                                             ^^^^^^^^^^
+  |                                             Any is not a valid export prefix, since it is not an immutable path
+  |
+  | longer explanation available when compiling with `-explain`
+-- Error: tests/neg/i20511-1.scala:7:56 --------------------------------------------------------------------------------
+7 |export toppingPrice.apply, crustPrice.apply, crustPrice.unlift // error // error // error // error // error
+  |                                                        ^^^^^^
+  |                                          no eligible member unlift at {
+  |                                            def $anonfun(crustType: Double): Double = pakiet.crustPrice(crustType)
+  |                                            closure(pakiet.$anonfun:Any)
+  |                                          }

tests/neg/i20511-1.scala

@@ -4,4 +4,4 @@ def toppingPrice(size: Int): Double = ???
 
 def crustPrice(crustType: Double): Double = ???
 
-export toppingPrice.apply, crustPrice.unlift // error // error // error
+export toppingPrice.apply, crustPrice.apply, crustPrice.unlift // error // error // error // error // error

tests/neg/i20511.check

@@ -0,0 +1,12 @@
+-- [E040] Syntax Error: tests/neg/i20511.scala:7:19 --------------------------------------------------------------------
+7 |export toppingPrice, crustPrice // error // error
+  |                   ^
+  |                   '.' expected, but ',' found
+-- [E040] Syntax Error: tests/neg/i20511.scala:8:0 ---------------------------------------------------------------------
+8 |val i = 1 // error
+  |^^^
+  |'.' expected, but 'end of statement' found
+-- Error: tests/neg/i20511.scala:7:21 ----------------------------------------------------------------------------------
+7 |export toppingPrice, crustPrice // error // error
+  |                     ^^^^^^^^^^
+  |                     Export selector must have prefix and `.`