Add extension method for copying a MethodNode

Signed-off-by: Graham <gpe@openrs2.dev>

asm/src/main/java/dev/openrs2/asm/MethodNodeUtils.kt

@@ -133,3 +133,15 @@ fun MethodNode.removeDeadCode(owner: String) {
 fun MethodNode.hasCode(): Boolean {
     return access and (Opcodes.ACC_NATIVE or Opcodes.ACC_ABSTRACT) == 0
 }
+
+fun MethodNode.copy(): MethodNode {
+    val copy = MethodNode(
+        access,
+        name,
+        desc,
+        signature,
+        exceptions?.toTypedArray()
+    )
+    accept(copy)
+    return copy
+}

deob/src/main/java/dev/openrs2/deob/transform/ConstantArgTransformer.kt

@@ -4,6 +4,7 @@ import com.github.michaelbull.logging.InlineLogger
 import dev.openrs2.asm.MemberRef
 import dev.openrs2.asm.classpath.ClassPath
 import dev.openrs2.asm.classpath.Library
+import dev.openrs2.asm.copy
 import dev.openrs2.asm.createIntConstant
 import dev.openrs2.asm.deleteExpression
 import dev.openrs2.asm.hasCode
@@ -105,14 +106,7 @@ class ConstantArgTransformer : Transformer() {
          * final pass, as we might discover more routes through the call graph
          * later which reduce the number of branches we can simplify.
          */
-        val method = MethodNode(
+        val method = originalMethod.copy()
-            originalMethod.access,
-            originalMethod.name,
-            originalMethod.desc,
-            originalMethod.signature,
-            originalMethod.exceptions?.toTypedArray()
-        )
-        originalMethod.accept(method)
 
         // find existing constant arguments
         val args = getArgs(ref)