Fix workflow (.makeEventHandler)

Author: AlbertShown

source/webui/package.d

@@ -1290,6 +1290,15 @@ const(void)* toWebUIBuffer(const(ubyte)[] data, int* length) @system
 
 // -- Callback adaptation -----------------------------------------------------
 
+/// Get the argument at `index` as raw bytes the callback owns.
+const(ubyte)[] copyRawAt(Event* e, size_t index) @trusted
+{
+    // `getRawAt` borrows from WebUI and dies when the handler returns, so the
+    // copy happens here rather than in the caller. That keeps this `@trusted`
+    // honest and lets a `@safe` handler take a `const(ubyte)[]` parameter.
+    return e.getRawAt(index).dup;
+}
+
 /// Wrap any supported callable into the uniform handler the dispatcher calls.
 EventHandler makeEventHandler(F)(F fn)
 {
@@ -1326,13 +1335,7 @@ EventHandler makeEventHandler(F)(F fn)
                 else static if (is(P == string) || is(P == const(char)[]))
                     args[i] = e.getStringAt(argIndex++);
                 else static if (is(P == const(ubyte)[]) || is(P == const(void)[]))
-                {
-                    // Hand the callback an owned copy rather than the slice
-                    // borrowed from WebUI, so a `@safe` handler cannot end up
-                    // holding a dangling reference after it returns.
-                    const rawIndex = argIndex++;
-                    args[i] = () @trusted { return e.getRawAt(rawIndex).dup; }();
-                }
+                    args[i] = copyRawAt(e, argIndex++);
                 else
                     static assert(false,
                         "webui.bind: unsupported parameter type `" ~ P.stringof