:pparse() should still raise an error if it is caused by misconfiguration

spec/pparse_spec.lua

@@ -16,4 +16,11 @@ describe("tests related to :pparse()", function()
       assert.is_false(ok)
       assert.equal("too few arguments", errmsg)
    end)
+
+   it("still raises an error if it is caused by misconfiguration", function()
+      local parser = Parser()
+      parser:option "--foo"
+         :count "a lot"
+      assert.has_error(function() parser:pparse{} end)
+   end)
 end)

src/argparse.lua

@@ -778,6 +778,7 @@ function Parser:pparse(args)
    if ok then
       return true, result
    else
+      assert(errmsg, result)
       return false, errmsg
    end
 end