more descriptive errors

src/index.js

@@ -62,7 +62,7 @@ importButton.onclick = async (ev) => {
         return;
     }
     if (files.length > 1) {
-        throw new Error("unreachable: something went wrong !");
+        throw new Error("unreachable: something went wrong ! files.length > 1");
     }
     const item = Vermiparous.de(await fetch(URL.createObjectURL(files[0])).then((x) => x.bytes()));
 };

src/vermiparous.js

@@ -42,7 +42,7 @@ export class Vermiparous {
         while (idx < bytes.length) {
             buffer.push(bytes[idx]);
             if (buffer.length >= MAX_KW_LENGTH) {
-                throw new Error("unreachable: something went wrong !");
+                throw new Error("unreachable: something went wrong ! unrecognized action");
             }
             if (buffer.length < MIN_KW_LENGTH || !isKeyword(buffer)) {
                 ++idx;