FIX: better error messages for not caught throws

Author: Oldes

src/boot/errors.reb

@@ -19,7 +19,8 @@ Throw: [
 	type: "throw error"
 	break:              {no loop to break}
 	return:             {return or exit not in function}
-	throw:              [{no catch for throw:} :arg1]
+	unnamed-throw:      [{no catch for unnamed throw with value:} :arg1]
+	throw:              [{no catch for throw:} :arg2 "with value:" :arg1]
 	continue:           {no loop to continue}
 	halt:               [{halted by user or script}]
 	quit:               [{user script quit}]

src/core/s-mold.c

@@ -1046,6 +1046,8 @@ STOID Mold_Error(REBVAL *value, REB_MOLD *mold, REBFLG molded)
 {
 	ERROR_OBJ *err;
 	REBVAL *msg;  // Error message block
+	REBCNT sym;
+	REBVAL word;
 
 	// Protect against recursion. !!!!
 
@@ -1062,9 +1064,21 @@ STOID Mold_Error(REBVAL *value, REB_MOLD *mold, REBFLG molded)
 		return;
 	}
 
-	// If it is an unprocessed BREAK, THROW, CONTINUE, RETURN:
-	if (VAL_ERR_NUM(value) < RE_NOTE || !VAL_ERR_OBJECT(value)) {
-		VAL_ERR_OBJECT(value) = Make_Error(VAL_ERR_NUM(value), value, 0, 0); // spoofs field
+	// If it is an unprocessed THROW:
+	if (VAL_ERR_NUM(value) == RE_THROW) {
+		sym = VAL_ERR_SYM(value);
+		if (!sym) {
+			VAL_ERR_OBJECT(value) = Make_Error(RE_UNNAMED_THROW, VAL_ERR_VALUE(value), 0, 0);
+		}
+		else {
+			Set_Word(&word, sym, 0, 0);
+			VAL_SET(&word, REB_WORD);
+			VAL_ERR_OBJECT(value) = Make_Error(VAL_ERR_NUM(value), VAL_ERR_VALUE(value), &word, 0);
+		}
+	}
+	// If it is an unprocessed BREAK, CONTINUE, RETURN:
+	else if (VAL_ERR_NUM(value) < RE_NOTE || !VAL_ERR_OBJECT(value)) {
+		VAL_ERR_OBJECT(value) = Make_Error(VAL_ERR_NUM(value), VAL_ERR_VALUE(value), 0, 0); // spoofs field
 	}
 	err = VAL_ERR_VALUES(value);