fix(service): fix checking folded if-condition when detecting unreach…

…able

crates/service/src/checker/unreachable.rs

@@ -152,6 +152,9 @@ impl Checker<'_> {
                 }
             }
             Instr::Block(BlockInstr::If(block_if)) => {
+                block_if
+                    .instrs()
+                    .try_for_each(|instr| self.check_instr(&instr, parent_block, unreachable));
                 let if_branch = block_if
                     .then_block()
                     .is_some_and(|block| self.check_block_like(block.syntax()));

crates/service/tests/diagnostics/snapshots/features__diagnostics__unreachable__folded_block_if.snap

@@ -0,0 +1,28 @@
+---
+source: crates/service/tests/diagnostics/unreachable.rs
+expression: response
+---
+{
+  "kind": "full",
+  "items": [
+    {
+      "range": {
+        "start": {
+          "line": 7,
+          "character": 6
+        },
+        "end": {
+          "line": 9,
+          "character": 13
+        }
+      },
+      "severity": 2,
+      "code": "unreachable",
+      "source": "wat",
+      "message": "unreachable code",
+      "tags": [
+        1
+      ]
+    }
+  ]
+}

crates/service/tests/diagnostics/unreachable.rs

@@ -336,3 +336,24 @@ fn folded_plain_instr() {
     let response = service.pull_diagnostics(create_params(uri));
     assert_json_snapshot!(response);
 }
+
+#[test]
+fn folded_block_if() {
+    let uri = "untitled:test".parse::<Uri>().unwrap();
+    let source = "
+(module
+  (func (param i32)
+    (if
+      (local.get 0)
+      (unreachable
+        (nop))
+      (nop)
+      (then)
+      (else))))
+";
+    let mut service = LanguageService::default();
+    service.commit(uri.clone(), source.into());
+    disable_other_lints(&mut service, uri.clone());
+    let response = service.pull_diagnostics(create_params(uri));
+    assert_json_snapshot!(response);
+}