fix meta-merging logic

oops :(

example/deno.jsonc

@@ -7,6 +7,7 @@
         "@eno/iso": "http://localhost:4507/lib/iso.tsx"
     },
     "tasks": {
-        "dev": "deno run -A --unstable --reload=http://localhost:4507/ --no-lock app.tsx --dev"
+        "dev": "deno run -A --unstable --reload=http://localhost:4507/ --no-lock app.tsx --dev",
+        "run": "deno run -A --unstable --reload=http://localhost:4507/ --no-lock app.tsx"
     }
 }

lib/iso.tsx

@@ -48,13 +48,14 @@ export const Meta =
                     const lookup = key as MetaKeys
                     const valPrev = final[lookup];
                     const valCurr = curr[lookup];
-                    if(valPrev && valCurr && curr.concatListed)
+
+                    if(valPrev && !valCurr)
                     {
-                        final[lookup] = valPrev + curr.concatListed + valCurr;
+                        final[lookup] = curr.dropUnlisted ? "" : valPrev;
                     }
-                    else if(!valCurr && curr.dropUnlisted)
+                    else if(valPrev && valCurr)
                     {
-                        final[lookup] = "";
+                        final[lookup] = curr.concatListed ? valPrev + curr.concatListed + valCurr : valCurr
                     }
                     else
                     {