perf(compose): check if it is a instance only once (honojs#3585)

* perf(compose): check if it is a instance only once

* chore: fix syntax

* chore: sort if condition

src/compose.ts

@@ -37,6 +37,8 @@ export const compose = <C extends ComposeContext, E extends Env = Env>(
 ): ((context: C, next?: Function) => Promise<C>) => {
   return (context, next) => {
     let index = -1
+    const isContext = context instanceof Context
+
     return dispatch(0)
 
     /**
@@ -58,15 +60,15 @@ export const compose = <C extends ComposeContext, E extends Env = Env>(
 
       if (middleware[i]) {
         handler = middleware[i][0][0]
-        if (context instanceof Context) {
+        if (isContext) {
           context.req.routeIndex = i
         }
       } else {
         handler = (i === middleware.length && next) || undefined
       }
 
       if (!handler) {
-        if (context instanceof Context && context.finalized === false && onNotFound) {
+        if (isContext && context.finalized === false && onNotFound) {
           res = await onNotFound(context)
         }
       } else {
@@ -75,7 +77,7 @@ export const compose = <C extends ComposeContext, E extends Env = Env>(
             return dispatch(i + 1)
           })
         } catch (err) {
-          if (err instanceof Error && context instanceof Context && onError) {
+          if (err instanceof Error && isContext && onError) {
             context.error = err
             res = await onError(err, context)
             isError = true