Cleanup soa resize logic—reduce nesting

base/runtime/core_builtin_soa.odin

@@ -249,14 +249,19 @@ _reserve_soa :: proc(array: ^$T/#soa[dynamic]$E, capacity: int, zero_memory: boo
 
 	old_data := (^rawptr)(array)^
 
-	if old_data != nil {
+	resize: if old_data != nil {
+
 		new_bytes, resize_err := array.allocator.procedure(
 			array.allocator.data, .Resize_Non_Zeroed, new_size, max_align,
 			old_data, old_size, loc,
 		)
 		new_data := raw_data(new_bytes)
 
-		if resize_err == .None {
+		#partial switch resize_err {
+		case .Mode_Not_Implemented: break resize
+		case .None: // continue resizing
+		case: return resize_err
+		}
 
 		footer.cap = capacity
 
@@ -268,8 +273,8 @@ _reserve_soa :: proc(array: ^$T/#soa[dynamic]$E, capacity: int, zero_memory: boo
 		// to:   |x x _ y y _ z z _|
 
 		// move old data to the end of the new allocation to avoid overlap
-			old_start := uintptr(new_data) + uintptr(new_size - old_size)
-			mem_copy(rawptr(old_start), new_data, old_size)
+		old_data = rawptr(uintptr(new_data) + uintptr(new_size - old_size))
+		mem_copy(old_data, new_data, old_size)
 
 		// now:  |_ _ _ x x y y z z|
 
@@ -280,7 +285,7 @@ _reserve_soa :: proc(array: ^$T/#soa[dynamic]$E, capacity: int, zero_memory: boo
 			new_offset = align_forward_int(new_offset, max_align)
 
 			new_data_elem := rawptr(uintptr(new_data) + uintptr(new_offset))
-				old_data_elem := rawptr(old_start + uintptr(old_offset))
+			old_data_elem := rawptr(uintptr(old_data) + uintptr(old_offset))
 
 			old_size_elem := type.size * old_cap
 			new_size_elem := type.size * capacity
@@ -300,11 +305,6 @@ _reserve_soa :: proc(array: ^$T/#soa[dynamic]$E, capacity: int, zero_memory: boo
 		return nil
 	}
 
-		if resize_err != .Mode_Not_Implemented {
-			return resize_err
-		}
-	}
-
 	new_bytes := array.allocator.procedure(
 		array.allocator.data, .Alloc if zero_memory else .Alloc_Non_Zeroed, new_size, max_align,
 		nil, old_size, loc,