diff --git a/crates/nu-cmd-lang/src/core_commands/const_.rs b/crates/nu-cmd-lang/src/core_commands/const_.rs
index e9fe52ba06..e20d2e2915 100644
--- a/crates/nu-cmd-lang/src/core_commands/const_.rs
+++ b/crates/nu-cmd-lang/src/core_commands/const_.rs
@@ -46,7 +46,9 @@ impl Command for Const {
         call: &Call,
         _input: PipelineData,
     ) -> Result<PipelineData, ShellError> {
-        let call = call.assert_ast_call()?; //FIXME
+        // This is compiled specially by the IR compiler. The code here is never used in when
+        // running in IR mode.
+        let call = call.assert_ast_call()?;
         let var_id = if let Some(id) = call.positional_nth(0).and_then(|pos| pos.as_var()) {
             id
         } else {
diff --git a/crates/nu-cmd-lang/src/core_commands/for_.rs b/crates/nu-cmd-lang/src/core_commands/for_.rs
index a56bf1dbb6..7ba152f391 100644
--- a/crates/nu-cmd-lang/src/core_commands/for_.rs
+++ b/crates/nu-cmd-lang/src/core_commands/for_.rs
@@ -48,7 +48,9 @@ impl Command for For {
         call: &Call,
         _input: PipelineData,
     ) -> Result<PipelineData, ShellError> {
-        let call = call.assert_ast_call()?; // FIXME
+        // This is compiled specially by the IR compiler. The code here is never used in when
+        // running in IR mode.
+        let call = call.assert_ast_call()?;
         let head = call.head;
         let var_id = call
             .positional_nth(0)
diff --git a/crates/nu-cmd-lang/src/core_commands/if_.rs b/crates/nu-cmd-lang/src/core_commands/if_.rs
index 79c266f8a2..c17c198414 100644
--- a/crates/nu-cmd-lang/src/core_commands/if_.rs
+++ b/crates/nu-cmd-lang/src/core_commands/if_.rs
@@ -60,7 +60,9 @@ impl Command for If {
         call: &Call,
         input: PipelineData,
     ) -> Result<PipelineData, ShellError> {
-        let call = call.assert_ast_call()?; // FIXME
+        // This is compiled specially by the IR compiler. The code here is never used in when
+        // running in IR mode.
+        let call = call.assert_ast_call()?;
         let cond = call.positional_nth(0).expect("checked through parser");
         let then_block = call
             .positional_nth(1)
@@ -100,7 +102,9 @@ impl Command for If {
         call: &Call,
         input: PipelineData,
     ) -> Result<PipelineData, ShellError> {
-        let call = call.assert_ast_call()?; // FIXME
+        // This is compiled specially by the IR compiler. The code here is never used in when
+        // running in IR mode.
+        let call = call.assert_ast_call()?;
         let cond = call.positional_nth(0).expect("checked through parser");
         let then_block = call
             .positional_nth(1)
diff --git a/crates/nu-cmd-lang/src/core_commands/let_.rs b/crates/nu-cmd-lang/src/core_commands/let_.rs
index acb3fd5859..45740e1ee2 100644
--- a/crates/nu-cmd-lang/src/core_commands/let_.rs
+++ b/crates/nu-cmd-lang/src/core_commands/let_.rs
@@ -46,7 +46,9 @@ impl Command for Let {
         call: &Call,
         input: PipelineData,
     ) -> Result<PipelineData, ShellError> {
-        let call = call.assert_ast_call()?; // FIXME
+        // This is compiled specially by the IR compiler. The code here is never used in when
+        // running in IR mode.
+        let call = call.assert_ast_call()?;
         let var_id = call
             .positional_nth(0)
             .expect("checked through parser")
diff --git a/crates/nu-cmd-lang/src/core_commands/loop_.rs b/crates/nu-cmd-lang/src/core_commands/loop_.rs
index 54fa234236..b5059fe918 100644
--- a/crates/nu-cmd-lang/src/core_commands/loop_.rs
+++ b/crates/nu-cmd-lang/src/core_commands/loop_.rs
@@ -37,7 +37,9 @@ impl Command for Loop {
         call: &Call,
         _input: PipelineData,
     ) -> Result<PipelineData, ShellError> {
-        let call = call.assert_ast_call()?; // FIXME
+        // This is compiled specially by the IR compiler. The code here is never used in when
+        // running in IR mode.
+        let call = call.assert_ast_call()?;
         let head = call.head;
         let block_id = call
             .positional_nth(0)
diff --git a/crates/nu-cmd-lang/src/core_commands/match_.rs b/crates/nu-cmd-lang/src/core_commands/match_.rs
index f49dd27c43..468ecfaa29 100644
--- a/crates/nu-cmd-lang/src/core_commands/match_.rs
+++ b/crates/nu-cmd-lang/src/core_commands/match_.rs
@@ -43,7 +43,9 @@ impl Command for Match {
         call: &Call,
         input: PipelineData,
     ) -> Result<PipelineData, ShellError> {
-        let call = call.assert_ast_call()?; // FIXME
+        // This is compiled specially by the IR compiler. The code here is never used in when
+        // running in IR mode.
+        let call = call.assert_ast_call()?;
         let value: Value = call.req(engine_state, stack, 0)?;
         let matches = call
             .positional_nth(1)
diff --git a/crates/nu-cmd-lang/src/core_commands/mut_.rs b/crates/nu-cmd-lang/src/core_commands/mut_.rs
index e03af856a1..bf6860c5be 100644
--- a/crates/nu-cmd-lang/src/core_commands/mut_.rs
+++ b/crates/nu-cmd-lang/src/core_commands/mut_.rs
@@ -46,7 +46,9 @@ impl Command for Mut {
         call: &Call,
         input: PipelineData,
     ) -> Result<PipelineData, ShellError> {
-        let call = call.assert_ast_call()?; // FIXME
+        // This is compiled specially by the IR compiler. The code here is never used in when
+        // running in IR mode.
+        let call = call.assert_ast_call()?;
         let var_id = call
             .positional_nth(0)
             .expect("checked through parser")
diff --git a/crates/nu-cmd-lang/src/core_commands/try_.rs b/crates/nu-cmd-lang/src/core_commands/try_.rs
index 97e7345a3d..065654ecc2 100644
--- a/crates/nu-cmd-lang/src/core_commands/try_.rs
+++ b/crates/nu-cmd-lang/src/core_commands/try_.rs
@@ -47,7 +47,9 @@ impl Command for Try {
         call: &Call,
         input: PipelineData,
     ) -> Result<PipelineData, ShellError> {
-        let call = call.assert_ast_call()?; // FIXME
+        // This is compiled specially by the IR compiler. The code here is never used in when
+        // running in IR mode.
+        let call = call.assert_ast_call()?;
         let try_block = call
             .positional_nth(0)
             .expect("checked through parser")
diff --git a/crates/nu-cmd-lang/src/core_commands/while_.rs b/crates/nu-cmd-lang/src/core_commands/while_.rs
index 98960dd414..79894484ec 100644
--- a/crates/nu-cmd-lang/src/core_commands/while_.rs
+++ b/crates/nu-cmd-lang/src/core_commands/while_.rs
@@ -46,7 +46,9 @@ impl Command for While {
         call: &Call,
         _input: PipelineData,
     ) -> Result<PipelineData, ShellError> {
-        let call = call.assert_ast_call()?; // FIXME
+        // This is compiled specially by the IR compiler. The code here is never used in when
+        // running in IR mode.
+        let call = call.assert_ast_call()?;
         let head = call.head;
         let cond = call.positional_nth(0).expect("checked through parser");
         let block_id = call