Survive unexpected function types after errors are reported.

If errors were already reported, the types function cannot be guaranteed to
be TermRefs anymore.

Author: odersky

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

@@ -987,7 +987,10 @@ trait Applications extends Compatibility {
 
   /** Overridden in ReTyper to handle primitive operations that can be generated after erasure */
   protected def handleUnexpectedFunType(tree: untpd.Apply, fun: Tree)(implicit ctx: Context): Tree =
-    throw new Error(i"unexpected type.\n  fun = $fun,\n  methPart(fun) = ${methPart(fun)},\n  methPart(fun).tpe = ${methPart(fun).tpe},\n  tpe = ${fun.tpe}")
+    if ctx.reporter.errorsReported then
+      throw TypeError(i"unexpected function type: ${methPart(fun).tpe}")
+    else
+      throw Error(i"unexpected type.\n  fun = $fun,\n  methPart(fun) = ${methPart(fun)},\n  methPart(fun).tpe = ${methPart(fun).tpe},\n  tpe = ${fun.tpe}")
 
   def typedNamedArgs(args: List[untpd.Tree])(implicit ctx: Context): List[NamedArg] =
     for (arg @ NamedArg(id, argtpt) <- args) yield {

tests/neg/i7816.scala

@@ -0,0 +1,4 @@
+object A {
+    def f()(>) = ???     // error
+    import f.NonExistent // error
+}