Fixes #25997 - nimsuggest SIGSEGV on ideType queries for void procs and module symbols (#25998)

Fixes #25997

`executeNoHooksV3`'s `ideType` handler dereferences the target symbol's
type
without nil checks, so nimsuggest (v3/v4) dies with SIGSEGV on a `type`
query for any symbol without a usable type:

- a **void proc** — `s.sym.typ[0]` (the return-type slot) is nil, e.g.
  "goto type definition" on the `add` in `s.add('x')`;
- a **module symbol** — `s.sym.typ` is nil, e.g. a `type` query on the
  module name in an `import` statement.

Both are one editor action away for any user whose client maps
`textDocument/typeDefinition` to `type` (nimlangserver does), and the
crash
takes down the whole nimsuggest process. Root-caused from recurring
nimlangserver crash reports by replaying a live session log; reproduced
deterministically with a two-line file.

The fix guards the derefs and returns an empty result for symbols with
no
type, matching the existing "bad type" behavior. Two regression cases
are
appended to `nimsuggest/tests/tv3_typeDefinition.nim` (appended at the
end
so the existing `$1`–`$4` line-number expectations are untouched); both
crash with `SIGSEGV: Illegal storage access` before the fix and pass
after.
The existing `$3` generic case covers the guarded `elif` branch.

nimsuggest/nimsuggest.nim

@@ -1156,13 +1156,14 @@ proc executeNoHooksV3(cmd: IdeCmd, file: AbsoluteFile, dirtyfile: AbsoluteFile,
       graph.suggestResult(s.sym, s.sym.info)
   of ideType:
     let s = graph.findSymData(file, line, col)
-    if not s.isNil:
+    if not s.isNil and s.sym.typ != nil:
       let typeSym = s.sym.typ.sym
       if typeSym != nil:
         graph.suggestResult(typeSym, typeSym.info, ideType)
-      elif s.sym.typ.len != 0:
+      elif s.sym.typ.len != 0 and s.sym.typ[0] != nil:
         let genericType = s.sym.typ[0].sym
-        graph.suggestResult(genericType, genericType.info, ideType)
+        if genericType != nil:
+          graph.suggestResult(genericType, genericType.info, ideType)
   of ideUse, ideDus:
     let symbol = graph.findSymData(file, line, col)
     if not symbol.isNil:

nimsuggest/tests/tv3_typeDefinition.nim

@@ -20,6 +20,13 @@ echo fo#[!]#oGeneric.bar
 # bad type
 echo unde#[!]#fined
 
+# type of a void proc: typ[0] (return type) is nil, must not crash
+var s = ""
+s.a#[!]#dd('x')
+
+# type of a module symbol: typ is nil, must not crash
+import std/str#[!]#utils
+
 discard """
 $nimsuggest --v3 --tester $file
 >type $1
@@ -29,4 +36,6 @@ type	skType	tv3_typeDefinition.Foo2	Foo2	$file	11	2	""	100
 >type $3
 type	skType	tv3_typeDefinition.FooGeneric	FooGeneric	$file	14	2	""	100
 >type $4
+>type $5
+>type $6
 """