FIX: HELP was providing invalid info if value of path was of ERROR! type

fixes: metaeducation/rebol-issues#2308

With this modification it works like:

```
>> help foo
No information on foo
>> help foo/boo
No information on foo/boo (path has no value)
>> help system/foo
There is no foo in path system/foo
>> ? system/state/last-error
SYSTEM/STATE/LAST-ERROR is a none of value: none
>> 1 / 0
** Math error: attempt to divide by zero
** Where: /
** Near: / 0

>> ? system/state/last-error
SYSTEM/STATE/LAST-ERROR is an error of value: make error! [
    code: 400
    type: 'Math
    id: 'zero-divide
    arg1: none
    arg2: none
    arg3: none
    near: [/ 0]
    where: [/]
]
```

Author: Oldes

src/mezz/mezz-help.r

@@ -238,12 +238,22 @@ dump-obj: function [
 
 	; Get value (may be a function, so handle with ":")
 	either path? :word [
-		if any [
-			error? set/any 'value try [get :word] ;try reduce [to-get-path word]
-			not value? 'value
-		][
-			print ["No information on" word "(path has no value)"]
-			exit
+		if error? set/any 'value try [get :word][
+			;check if value is error or if it was really an invalid or path without value
+			if all [
+				value/id   = 'invalid-path
+				value/arg1 = :word
+			][
+				print ["There is no" value/arg2 "in path" value/arg1]
+				exit
+			]
+			if all [
+				value/id = 'no-value
+				value/arg1 = first :word
+			][
+				print ["No information on" word "(path has no value)"]
+				exit
+			]
 		]
 	][
 		value: get :word