FEAT: any TRY call resets system/state/last-error to none

related to: Oldes/Rebol-issues#2419

src/core/n-control.c

@@ -834,13 +834,13 @@ enum {
 {
 	REBFLG except = D_REF(2);
 	REBVAL handler = *D_ARG(3); // TRY exception will trim the stack
+	REBVAL *last_error = Get_System(SYS_STATE, STATE_LAST_ERROR);
+	SET_NONE(last_error);
 
 	if (Try_Block(VAL_SERIES(D_ARG(1)), VAL_INDEX(D_ARG(1)))) {
+		// save the error as a system/state/last-error value
+		*last_error = *DS_NEXT;
 		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

@@ -505,6 +505,13 @@ Rebol [
 			--assert error? system/state/last-error
 			--assert system/state/last-error/id = 'zero-divide
 		]
+		; any TRY call resets system/state/last-error to none:
+		--assert not error? try [1 + 1]
+		--assert none? system/state/last-error
+		; the last-error is stored also when /except is not used:
+		--assert error? try [this-is-error]
+		--assert error? system/state/last-error
+
 	--test-- "try/except [1 / 0] function!"
 		system/state/last-error: none
 		--assert string? try/except [1 / 0] :mold