FIX: TRY/except should store the last-error

Now one can access the last error from exception block handler:
```
>> x: 0 try/except [1 / 0][ if 'zero-divide = system/state/last-error/id [ print "OK" x: 1] ] x
OK
== 1

```

Fixes: Oldes/Rebol-issues#2419

Author: Oldes

src/core/n-control.c

@@ -837,6 +837,10 @@ enum {
 
 	if (Try_Block(VAL_SERIES(D_ARG(1)), VAL_INDEX(D_ARG(1)))) {
 		if (except) {
+			// save it for access from the block handler or explain
+			REBVAL *val = Get_System(SYS_STATE, STATE_LAST_ERROR);
+			*val = *DS_NEXT;
+
 			if (IS_BLOCK(&handler)) {
 				DO_BLK(&handler);
 			}

src/tests/units/evaluation-test.r3

@@ -471,6 +471,23 @@ Rebol [
 ===end-group===
 
 
+===start-group=== "TRY/except"
+	--test-- "try/except [1 / 0] block!"
+	;@@ https://github.com/Oldes/Rebol-issues/issues/2419
+		system/state/last-error: none
+		try/except [1 / 0][
+			--assert error? system/state/last-error
+			--assert system/state/last-error/id = 'zero-divide
+		]
+	--test-- "try/except [1 / 0] function!"
+		system/state/last-error: none
+		--assert string? try/except [1 / 0] :mold
+		--assert system/state/last-error/id = 'zero-divide
+
+
+===end-group===
+
+
 ===start-group=== "delta-profile"
 
 	--test-- "delta-profile []"