temporary workaround for janet try macro hygiene bug

This code should work regardless of the Janet version used, and we can back
it out after janet-lang/janet#1659 lands upstream.

Author: ianthehenry

src/jlsl/types.janet

@@ -112,7 +112,7 @@
           (put functions-called function (table/proto-flatten scope))
           (def args-and-params (try
             (zip args (function/param-sigs function))
-            ([_]
+            ([_ __]
               (errorf "wrong number of arguments to function %s, expected %q, got %q"
                 (/name function)
                 (length (function/param-sigs function))

tests/suite.janet

@@ -819,7 +819,7 @@ img {
 
     (def old-file-name (try
       (slice ($<_ git show HEAD:tests/ ^ ,ref-path >[stderr :null]) 3)
-      ([_] nil)))
+      ([_ __] nil)))
     ($ ln -fs (string "../" new-file-name) ,ref-path)
 
     (def changed? (and old-file-name (not= old-file-name new-file-name)))